Aromatherapy: Aromatherapy is the systematic, controlled use of essential oils to promote and enhance the health and well being of the individual.
Abortifacient: Capable of inducing a miscarriage.
Absolute: Highly concentrated, highly fragrant, thickish, coloured liquid that
can be prepared from a concrete using alcohol, e.g. jasmine. Absolutes can
also be produced by enfleurage and carbon dioxide extraction.
Adaptogen: Used to describe essential oils that act as natural balancers.
These oils are able to react in what appears to be opposite ways depending
upon the needs of the body. For example, peppermint oil can both relax and
Adipose tissue: Closely packed cells containing fat, found in the
subcutaneous layer of the skin and around the kidneys, heart and blood
vessels. It provides an energy store, heat insulation and mechanical
Adulteration: An unfavorable practice to the Aromatherapist, in which the oil
is 'stretched' in some way by adding alcohol, another cheaper oil or a
Alcohol: Alcohols are the most beneficial group of chemicals to the
Aromatherapist. They are generally very safe and effective. Alcohols are
aliphatic and are derived from two isoprene units. They form esters,
aldehydes and acids. They are generally antiseptic, anti-viral, bactericidal,
stimulating and uplifting. Examples include linalool (lavender and bergamot),
citronellol (rose (cabbage) and geranium) and geraniol (palmarosa and
geranium). As essential oils dissolve in alcohol, alcohol is often used during
solvent extraction. Alcohols are also be used to adulterate oils.
Aldehyde: A chemical compound found in many essential oils. Aldehydes are
formed from alcohols that have been dehydrogenated (had water removed).
They are derived from 2 isoprene units plus a carbonyl group (carbon,
hydrogen and oxygen) and are often chemically reactive. Aldehydes generally
have a sedative, fungicidal and anti-inflammatory effect. Examples include
neral (melissa, lemongrass and grapefruit) and citral (lemongrass, bergamot
and melissa). They should be used with care as they can irritate the skin and
Aliphatic compound: Produced when atoms bond in chains. These chains
can branch to form aliphatic branching chains or curl around on themselves to
form aliphatic cyclic chains. They are simpler than aromatic compounds and
are generally non-fragranced.
Almond oil (sweet): Latin name: Prunus amygdalus var. dulcis. A very pale
yellow oil used as a carrier.
Anaemia: Deficiency of red blood cells or haemoglobin (the pigment of the
red blood cells responsible for transporting oxygen from the lungs to the
Analgesic: Relieves pain. Oils with an analgesic action include chamomile
(Roman), ginger, lavender, peppermint and rosemary.
Anaphrodisiac: Reduces sexual desire. Marjoram (sweet) oil has an
Anosmia: The loss or fading of the sense of smell.
Antibiotic: Combats infection in the body by preventing the growth of or
destroying bacteria. Oils with an antibiotic action include niaouli and tea-tree.
Antibodies: Protein molecules produced by lymphocytes to neutralise the
effect of foreign invading proteins (antigens). Antibody molecules attach
themselves to invading antigen molecules, rendering them inactive.
Anti-depressant: Aids to lift the mood, alleviating depression. Oils that have
an anti-depressant action include bergamot, clary-sage, geranium, jasmine,
may chang, neroli, orange (sweet), patchouli, petitgrain, rose,
sandalwood and ylang ylang.
Antidote: Medicine given to counteract poison.
Anti-emetic: Helps to control nausea or vomiting. Nutmeg oil has an anti-
Antigen: Foreign, invading particle.
Anti-histaminic: Counteracts the effects of histamine (a chemical found in all
body tissues causing some allergic reactions). Clove (bud) has an anti-
Anti-inflammatory: Reduces inflammation (heat, swelling, redness). Oils with
an anti-inflammatory action include chamomile (German), eucalyptus (blue
gum), may chang, myrrh and peppermint.
Anti-microbial: Fights or prevents pathogenic (disease causing) microorganisms.
Rosewood oil has an anti-microbial action.
Anti-neuralgic: Acts to relieve or reduce nerve pain. Oils with an anti-
neuralgic property include chamomile (Roman), clove (bud) and pine.
Anti-oxidant: Prevents or delays a reaction with oxygen. Clove (bud) oil has
an anti-oxidant action. Wheatgerm oil can also be added to a blend to extend
its shelf life.
Anti-rheumatic: Helps to relieve or prevent rheumatism (a disease
characterised by inflammation and pain in the joints). Nutmeg oil has an anti-
Antiseptic: Prevents the growth of or destroys microbes (bacteria that cause
disease). All essential oils are, to a degree, antiseptic. Those with particularly
effective antiseptic properties include basil (European), bergamot, citronella,
cedarwood (atlas), clove (bud), cypress, eucalyptus (blue gum), grapefruit,
geranium, juniperberry, lavender, lemon, lemongrass, may chang, niaouli,
palmarosa, petitgrain and rosewood. Myrrh and pine are both useful as a
pulmonary antiseptic. Sandalwood is a urinary antiseptic.
Anti-spasmodic: Prevents or relieves excessive muscular contractions or
convulsions. Oils with an anti-spasmodic action include basil (European),
chamomile (German and Roman), clary-sage, ginger, marjoram (sweet),
melissa, orange (sweet) and nutmeg.
Anti-sudorific: Counteracts perspiration.
Anti-toxic: Counteracts poisoning.
Anti-viral: Destroys or inhibits the growth of a virus. Oils with an anti-viral
action include bergamot, eucalyptus (blue gum), patchouli, pine and tea-tree.
Aphrodisiac: Increases sexual desire. Oils with an aphrodisiac action include
neroli and patchouli.
Apricot kernel oil: Latin name: Prunus armeniaca. Yellow fixed oil used as a
Aromatherapy Organisations Council: The AOC is a governing body for the
Aromatherapy profession in the UK. Its address is: PO Box 19834, London,
Aromatherapy: Aromatherapy is the systematic, controlled use of essential oils to promote and enhance the health and well being of the individual.
Aromatic compound: Aromatic compounds are characterised by a ring of 6
carbon atoms with alternate double covalent bonding. They are more
complex, more volatile and more unstable than aliphatic compounds. They are
irritants and, although they generally have a fragrance, some are odourless.
Aromatic waters: Created as a by-product of distillation. They contain some
soluble components of the essential oil together with some of the larger water-
soluble plant molecules. They do have some of the properties of the essential
Aromatology: The study of essential oils for health.
Arteriosclerosis: Hardening and thickening of the walls of the arteries.
Astringent: Causes the contraction of tissue. Oils with an astringent action
include cedarwood (atlas), cinnamon (leaf), cypress, frankincense,
juniperberry, lemongrass, may chang, rose (cabbage), rosemary and
Atom: The smallest and simplest matter that can take part in a chemical
reaction. An atom has a nucleus (central part) containing protons (positively
charged particles) and neutrons (particles with no electrical charge). The
nucleus is surrounded by a number of electrons (negatively charged
Autonomic nervous system: Part of the peripheral nervous system that
regulates the activity of smooth muscle (found in the walls of hollow
structures), cardiac muscle (found in the heart) and glands. It comprises of the
sympathetic and parasympathetic nervous systems.
Avicenna: (980-1037) A great Muslim philosopher, physician and scholar who
adapted the mechanism used for distillation by extending the cooling pipe to
form a coil, enabling the vapour to cool down quickly and more effectively. He
wrote 'The Book of Healing' and 'The Canon of Medicine'.
Avocado oil: Latin name: Persea americana. Sticky, dark green oil used as a
Bactericidal: Destroys bacteria. Oils with a bactericidal action include
eucalyptus (blue gum), lemon, may chang and tea-tree.
Balancing: Harmonises the mind, body and spirit. Bergamot oil has a
balancing action. Palmarosa oil acts to balance the hormones.
Balsamic: Soothing or healing. Oils with a balsamic action include niaouli and
Base oil: Alternative name for a carrier oil, i.e. an oil used to dilute and carry
essential oils into the body.
Bath crystals: Can be used as a means of adding essential oils to a bath.
Simply crush 250g of soda crystals, add 20 drops of oil and a little food
colouring. Use no more than 60g of crystals per bath.
Bath: A method of use in which essential oils are added to bath water. Oils
used in this way should be diluted in a carrier to 2.5%, or just 1% for children,
babies or expectant mothers.
Bidet: Method of use involving the application of diluted essential oils to the
vagina, urethra, labia and anus. Extreme care must be taken as the delicate
mucous membranes are easily irritated. Dilute 1-2 drops of essential oil in 1
teaspoon of vegetable oil. Run the warm water from the tap, add the mixture
and mix well.
Bile: A secretion of the liver that enters the duodenum (first part of the small
intestines) via the bile duct. Bile salts aid digestion.
Biosynthesis: The production of chemicals by a living cell.
Blending: The combining of one or more essential oils, usually with a carrier.
Oils are blended to create a mix with the desired therapeutic properties, the
required perfume or both.
Blood pressure: The pressure of blood against the walls of the blood
vessels, in particular the main arteries, that results from the pumping action of
the heart and the elasticity of the vessel walls. High and low blood pressure
are known as hypertension and hypotension respectively.
Blood: The fluid that is circulated in arteries, veins and capillaries by the
muscular contractions of the heart. It carries oxygen and nutrients to the
tissues and removes carbon dioxide and other waste products from the
tissues. It also transports hormones and circulates heat throughout the body.
Essential oils are absorbed into the blood system where they are quickly
carried around the whole body.
British Complementary Medicine Association: The aim of the BCMA is to
encourage "the diverse organisations of individual therapies to join together in
single therapy groups and act collectively". The BCMA has a code of conduct
that you should be familiar with. The address for the BCMA is 9 Soar Lane,
Leicester, LE3 5DE.
Bronchial dilator: Opens the bronchial tubes (air passages in the lungs).
May chang oil is a bronchial dilator.
Calendula oil: Latin name: Calendula officinalis. Used as a carrier.
Calmative: Sedating. Chamomile (German) has a calmative action.
Carbon dioxide extraction: Carbon dioxide is used at high pressure and low
temperature to extract absolutes. The oils produced are pure, stable, smell
exactly like the flower from which they were extracted and contain no trace of
Carbon: Chemical element occurring in all organic compounds.
Carbonyl group: A specific group of carbon, hydrogen and oxygen atoms.
Carboxyl group: A specific group of carbon and oxygen atoms.
Carminative: Settles the digestive system and relieves flatulence. Oils with a
carminative action include basil (European), black pepper, fennel (sweet),
lemongrass and patchouli.
Carrier oil: An oil used to dilute and carry essential oils into the body. Also
known as a base oil.
Carrot oil: Latin name: Daucus carota. Extracted from the root by maceration
and used as a carrier. Essential oil can be produced by the distillation of the
Case history: Full client details including current and past medical history.
There is a legal requirement to document this information, along with any
treatment and subsequent results. These details must be kept for a minimum
of 6 years.
Cell: The basic unit of structure of all living organisms (excluding viruses). All
cells contain genetic material (deoxyribonucleic acid or DNA) which controls
the cells activities.
Central nervous system: Comprises of the brain and the spinal cord. It
receives sensory information from all parts of the body, analyses the
information and then responds by sending impulses to stimulate muscles or
Cephalic: Clears the head. Oils with a cephalic action include basil
(European), hyssop and rosemary.
Chemotype: The term given to describe plants which, although they look the
same, may produce significantly different chemicals. This may be caused by
variations within a species, influences such as the environment in which they
are grown and the effects of cross-pollination.
Chlorophyll: The green pigment present in most plants, responsible for the
absorption of light energy during photosynthesis.
Chloroplast: Structure within a plant cell that contains the green pigment
Cholagogue: Stimulates the evacuation of the gall bladder, so increasing the
flow of bile into the duodenum. Pine oil has a cholagogue action.
Choleretic: Stimulates the liver to secrete more bile.
Cholesterol: A fat derivative found in animal cells that is insoluble in water. Its
presence on the inside of the walls of blood vessels is thought to contribute to
hypertension and thrombosis. It can also accumulate in the gall bladder as
Chromosome: A structure in the cell nucleus (centre) that carries the genes.
Each chromosome consists of one very long strand of DNA (deoxyribonucleic
acid). Humans usually have 23 pairs of chromosomes.
Cicatrisant: Promotes healing by the formation of scar tissue. Oils with a
cicatrisant action include rose (cabbage) and sandalwood.
Coconut oil: Latin name: Cocos nucifera. Does not occur naturally and the
end product is a fractionated (not whole) oil. Whilst it is used as a carrier oil,
its use must be questioned due to the harshness of the method of extraction.
Cold extraction: Preferred method of use for extracting carrier oils.
Vegetables, seeds or nuts are cold pressed to produce oils undamaged by
heat or by the addition of solvents.
Compound: Molecule made up of more than one type of atom. For example,
water is a compound made up of two hydrogen atoms and one oxygen atom,
hence its chemical formula H2O.
Compress: Hot and cold compresses are an effective way of relieving pain
and reducing inflammation. Cloths are soaked in a bowl of either very hot or
ice cold water containing 4-5 drops of essential oil. They are squeezed out
and then applied to the appropriate area until the temperature of the cloth is
the same as body temperature.
Concrete: Solid, wax-like substances (e.g. rose otto) that can be extracted
from plant materials such as leaves, flowers and roots using hydrocarbons
(e.g. benzine and hexane) as the solvent. The solvent is then removed by
Connective tissue: Supports, binds, connects and holds the organs of the
body in position.
Constipation: A condition in which defecation is irregular, difficult or
Contra-indications to Aromatherapy: Aspects of the client’s condition that
negatively affect your decision to treat. Contra-indications to Aromatherapy
may prevent treatment altogether, restrict the appropriate methods of use or
reduce the range of suitable oils. There is a list of contra-indications to
Aromatherapy in the 'Safety' section.
Contra-indications to massage: Aspects of the client’s condition that either
prevent massage taking place altogether or restrict its use to certain parts of
the body. There is a list of contra-indications to massage in the 'Methods of
Coumarins: A group of chemical compounds that fall in the lactone category.
Coumarins are anti-coagulant, uplifting and sedative. They are
Cream: Hypoallergenic, unperfumed creams can be used as carriers for
essential oils. Creams provide a medium to produce hand and body
preparations to be used topically at home.
Culpepper, Nicolas: A British astrologer-physician who, in the 17th century,
wrote a book called 'Arts Master Piece, or the beautifying part of Physick',
which consisted of recipes based on the use of aromatic herbs, gums, oils and
waters. He also wrote 'Complete Herbal'.
Cytophylactic: Promotes cell regeneration. Oils that have a cytophylactic
action include frankincense, lavender, neroli, palmarosa and tea-tree.
Debility: Weakness, feebleness.
Decongestant: Relieves the abnormal accumulation of substances such as
mucus. Eucalyptus (blue gum) has a decongestant action.
Deodorant: Corrects, masks or removes odours. Oils with a deodorant action
include citronella, cypress, eucalyptus (blue gum) and petitgrain.
Deoxyribonucleic acid (DNA): A complex two-stranded molecule, found in
chromosomes, that contains all the information needed to build, control and
maintain a living organism. It forms the basis for genetic inheritance.
Depurative: Combats impurity in the blood and organs. Grapefruit oil has a
Dermatitis: Inflammation of the skin.
Detoxifying: Helps to cleanse the body of impurities. Oils with a detoxifying
action include cypress, fennel (sweet), juniperberry and lemon.
Diffuser: The name given to a piece of equipment specially made to diffuse
the aroma of essential oils, often using heat.
Digestive: Aids the digestion of food. Oils with a digestive action include
chamomile (Roman), cinnamon (leaf), grapefruit, may chang, nutmeg and
Digitalis: Drug prepared from dried foxglove leaves, used as a heart
Distillation: The oldest, and most widely used, method of extracting essential
oils from plants. Plant material is heated from below with water/steam causing
the tiny, volatile, aromatic molecules to vaporise. This vapour is then
condensed and the essential oil separated from the water.
Diterpenes: Term given to terpenes that contain 4 isoprene units (20 carbon
atoms). They are not commonly found in essential oils, although sclareol
exists in clary sage.
Diuretic: Increases the production of urine. Oils with a diuretic action include
chamomile (German), citronella, cypress, fennel (sweet), grapefruit,
juniperberry and rosemary.
Douche: Method of use involving the application of diluted essential oils to the
vagina, urethra and labia. This method should only be used as directed by a
Electron: A negatively charged particle in an atom. Electrons surround the
nucleus of an atom.
Element: Molecule made up of only one type of atom. For example oxygen is
made up of two oxygen atoms, hence its chemical formula O2.
Emmenagogue: Stimulates menstruation. Oils with this action include
cinnamon (leaf), fennel (sweet) and marjoram (sweet).
Emollient: Substance which softens and smooths the skin.
Enfleurage: A method of extraction in which flowers are spread over cold
vegetable fat so allowing the aromatic molecules to be absorbed. When the
fat is saturated with the oil it is washed in alcohol. The alcohol is then
evaporated, leaving the absolute. This labour intensive method of extraction is
not commonly used these days.
Enzyme: Biological catalyst produced in cells capable of speeding up
chemical reactions. Enzymes are large, complex proteins and are not
destroyed during the chemical reactions that they promote.
Epilepsy: A nervous condition, characterised by fits, convulsions and a
sudden loss of consciousness. Some essential oils are contra-indicated to
epilepsy as they may induce a fit. They include fennel (sweet), hyssop,
peppermint, rosemary and thyme.
Essences: Odiferous chemicals found in plants.
Essential oil: Highly concentrated oil, extracted from plants, that can be used
therapeutically to treat both physical and emotional conditions.
Ester: A chemical compound found in many essential oils. Esters are formed
by the joining of an acid with an alcohol. Esters have a general fungicidal,
anti-spasmodic and sedative effect. For example linalyl acetate (bergamot,
clary-sage and lavender) and geranyl acetate (marjoram (sweet) and
Ether: An aromatic chemical compound rarely occurring naturally in essential
oils. Ethers are generally anti-depressant and sedative, balance the nervous
system, stimulate mental processes and reduce spasm. For example anethol
found in bitter fennel (a hazardous oil). Any oil containing ethers should be
used with care.
Evening primrose oil: Latin name: Oenothera biennis. Pale yellow oil used
as a carrier. It can be taken internally in capsule form and it is reputed to be
useful for reducing cholesterol and preventing heart disease.
Expectorant: Helps to expel phlegm/mucus from the respiratory system. Oils
that have an expectorant action include cedarwood (atlas), eucalyptus (blue
gum), hyssop, peppermint, pine and sandalwood.
Expression: A method used to extract essential oils from the rind of citrus
fruit by squeezing.
Facial sauna: A few drops of essential oil such as lemon or tea-tree can be
added to a bowl of hot water. Leaning over the bowl, allowing the steam to
come into contact with the face, can help to unclog the pores and to clear the
complexion. When using proper facial sauna equipment, read the instructions
Febrifugal: Combats fever. Oils that have a febrifugal action include
eucalyptus (blue gum), lemongrass, niaouli and palmarosa.
Fibrositis: Another name for muscular rheumatism.
Foot bath: An effective method of use that enables essential oils to quickly
penetrate the skin. 2-6 drops of oil are added to a bowl of warm water and the
feet are soaked for 20 minutes.
Fractionated oil: An oil that, usually as a result of a harsh method of
extraction, is not whole i.e. components of the essence are lost. Coconut oil,
used as a carrier, is an example of a fractionated oil.
Fungicidal: Combats fungal infections by inhibiting the growth of yeast. Oils
with a fungicidal action include lemongrass, may chang, myrrh, patchouli and
Furocoumarins: A group of chemical compounds that fall in the lactone
category. Furocoumarins are anti-fungal and anti-viral. They are
Gastritis: Inflammation of the stomach.
Gattefossé, Rene: A famous chemist who, in the early part of the 20th
century, coined the phrase ‘Aromatherapie’ after conducting many
experiments on the healing properties of essential oils, particularly lavender.
Gene: Unit of inherited material located on a chromosome that, by itself or
with other genes, determines a characteristic in an organism.
Glucoside: A product which on hydrolysis (chemically reacting with water)
produces glucose and other product(s).
Gluten: A constituent of wheatflour which, on addition of water, forms an
adhesive substance. It can be responsible for certain malabsorption disorders,
hence the introduction of gluten-free diets as a part of the treatment.
Grapeseed oil: Latin name: Vitis vinifera. A yellow, thin, non-greasy oil used
as a carrier.
Grounding: Gives a sense of emotional safety and realism i.e. with the 'feet
on the floor'. Oils with a grounding action include cedarwood (atlas) and
Haemostatic: Helps to stops bleeding. Geranium oil has a haemostatic
Hall, Cuthbert: Discovered in 1904 that the antiseptic power of eucalyptus oil
in its natural form was stronger than any of its isolated constituents.
Hallucinogenic: Causes delusions, bad dreams or visions. Oils that have an
hallucinogenic action include clary-sage and nutmeg.
Hand bath: A method of use in which 2-4 drops of essential oils are added to
a bowl of warm water and the hands soaked for a maximum of 10 minutes.
Hazardous oils: Oils that should never be used in Aromatherapy. There is a
list of hazardous oils in the 'Safety' section.
Hazelnut oil: Latin name: Corylus avellana. A yellow oil used as a carrier.
Hepatic: Tones and aids the function of the liver. Rose (cabbage) oil has a
Hildegard: A German Abbess who grew lavender in the 12th century for its
Hippocrates: A Greek physician around 400 B.C., later known as the ‘Father
of Medicine’, who was born and practiced on the Greek island of Cos. He
categorised the uses of a number of essential oils.
Holistic: Whole, encompassing all aspects. Within Aromatherapy, holistic
usually refers to mind, body and spirit.
Hormone: Product of the endocrine glands (e.g. hypothalamus, thyroid,
parathyroids, pituitary, adrenals, pancreas, pineal gland, thymus, ovaries and
testes). Hormones are concerned with the control of body functions and bring
about changes in the functions of various organs according to the body’s
Hot extraction: Means of extracting essential oils from plants using heat.
Hydrocarbon: A compound made up of hydrogen and carbon atoms.
Terpenes are hydrocarbons.
Hydro-diffusion: A method of extraction in which steam is passed down
through the plant material, causing the vaporisation of the tiny, volatile,
aromatic molecules. The vapour is then condensed and the essential oil
separated from the water. This method is otherwise known as percolation.
Hydroxyl group: A compound consisting of hydrogen and oxygen atoms.
Hyperallergenic: Above normal risk of allergic reaction.
Hypericum oil: Latin name: Hypericum perforatum. A ruby coloured
macerated oil used as a carrier. Otherwise known as St John’s Wort.
Hyperpnoea: Abnormally fast respiratory rate.
Hypertensive oils: Essential oils that may raise the blood pressure. These
include rosemary, black pepper, juniperberry, peppermint, thyme (white),
cinnamon (leaf), pine and clove (bud).
Hypoallergenic: Below normal risk of allergic reaction.
Hypochondria: A mental condition in which the sufferer has the delusion that
he or she is seriously ill. Depression often accompanies the anxiety.
Hypotensive oils: Essential oils that may lower the blood pressure. These
include lavender, lemon, marjoram (sweet), melissa, neroli, niaouli and ylang
Hypothalamus: Situated at the base of the brain, the hypothalamus is linked
by nerves to the olfactory centre. The hypothalamus is involved in many
regulatory and metabolic activities, e.g. body temperature, hormone release,
heart rate, respiratory rate, blood pressure, hunger and digestion. It also acts
as an emotional regulator capable of alleviating anxiety and depression.
Impetigo: Infectious skin disease in which small blisters appear, usually on
the face, and then dry to leave scabs. When the scabs fall off no scars are left
but, because the infection spreads over the skin, the condition may last for
Inhalation: The means by which essential oils are taken in to the body via the
respiratory system. It is the oldest, simplest and fastest way that essential oils
access the body. The inhalation of essential oils has a powerful effect on the
body via the olfactory system, which is responsible for the sense of smell. The
stimulation of the olfactory system can bring about physiological and
psychological changes and trigger strong memories.
Inorganic compound: Substance not containing carbon that is non-living or
has never lived.
Insecticidal: Repels insects. Oils with an insecticidal action include citronella,
eucalyptus (blue gum), lemongrass and peppermint.
Isomer: A chemical structure sharing the same molecular composition and
chemical formula as another, but with a different physical structure and
therefore different chemical properties.
Isoprene unit: A building block of many of the organic compounds found in
essential oils, consisting of 5 carbon atoms arranged in a set pattern.
Jacuzzi: A method of use in which 3 drops of essential oil per person are
added to the water in a jacuzzi. Anti-bacterial oils are particularly useful to
enhance the hygienic safety of a shared jacuzzi.
Jojoba oil: Latin name: Simmondsia chinensis. A yellow liquid wax used as a
Ketone: A chemical compound found in many essential oils. Ketones are
derived from 2 isoprene units plus a carboxyl group (consisting of carbon and
oxygen atoms) and are chemically reactive. Used for short periods in weak
dilution, ketones can be sedative and decongestant. They are contra-indicated
to pregnancy and the use of high ketone combinations should be avoided with
epileptics. Some ketones are toxic e.g thujone (found in sage and
wormwood). Examples of non-toxic ketones include jasmone (jasmine) and
Kiwang Ti: An Emperor of China around 2000 B.C.. He wrote a medical book
entitled the ‘Yellow Emperor’s Book of Internal Medicine’ which provides the
earliest known record of the properties of essential oils.
Lactone: A chemical compound commonly found in essential oils, particularly
expressed citrus oils. Lactones are made up of 3 isoprene units structured in
aliphatic cyclic chains. They are immuno-stimulants, expectorants, anti-
inflammatory and febrifugal. Lactones are known to cause photosensitivity,
may raise blood pressure and are anti-coagulant. Examples of lactones
include bergamottin (bergamot) and bergapten (bergamot and lemon). There
are 2 groups of lactones of interest to the Aromatherapist; (1) coumarins
which are sedative and calming yet uplifting and (2) furocoumarins which are
anti-fungal and anti-viral.
Laxative: Stimulates defecation. Rose (cabbage) oil has a laxative action.
Leucocyte: White blood cell that plays a part in the body’s natural defences
and immunity against disease. Leucocytes occur in the blood, lymph and
elsewhere in the body's tissues. Some engulf invading micro-organisms,
some kill infected cells, while lymphocytes (a type of white blood cell) produce
more specific immune responses.
Leucorrhoea: A symptom of many diseases characterised by thick, white
vaginal discharge consisting mainly of pus. Leucorrhoea is also known as
Lime blossom oil: Latin name: Tilia europra. A macerated oil used as a
Limited company: A means by which a minimum of 2 people can trade with
liability being limited to the value of the business.
Lipid: Fat or fat–like substance, commonly formed by the reaction of a fatty
acid with glycerol. Lipids are soluble in alcohol but not in water and are the
chief constituents of plant and animal waxes, fats and oils.
Lipophilic: Literally means to 'like fat'. The lipophilic property of essential oils
allows them to dissolve in fat.
Lotion: Hypoallergenic, unperfumed lotions can be used as carriers for
essential oils. Lotions provide a medium to produce hand and body
preparations to be used topically at home.
Lumbago: A painful condition affecting the muscles in the lower part of the
back. It is generally thought to be a rheumatic disorder but can also be
brought on by muscular strains.
Lymph: The used and excess tissue fluid that is drained from the intercellular
spaces into the vessels of the lymphatic system.
Lymphatic system: A series of vessels and associated lymph nodes in which
lymph is transported from the tissue fluids into the bloodstream. Lymph is
drained from the tissues by lymph capillaries, which empty into larger lymph
vessels. The lymph vessels lead to lymph nodes (found in the neck, axilla,
groin, thorax and abdomen) which process the lymphocytes produced by the
bone marrow and filter out harmful substances and bacteria. From the lymph
nodes the lymph is carried in larger vessels called lymphatic trunks. These
merge to form the larger lymph ducts. The lymph ducts join the circulatory
system and the lymph is drained into large veins that transport the blood to
Lymphatic: Stimulates or pertains to the lymphatic system. Oils with a
lymphatic action include geranium, grapefruit and rosemary.
Lymphocyte: Type of white blood cell produced mainly in the bone marrow.
Most occur in the lymph and blood and around sites of infection. There are 2
main types of lymphocyte; (1) B-lymphocytes that are responsible for
producing antibodies and (2) T-lymphocytes that have various roles to play in
Macadamia oil: Latin name: Macadamia integrifolia. A fairly stable oil with a
soft, golden colour and a faint smell, used as a carrier.
Maceration: A method of extracting oils from plants by plunging the flowers
into hot vegetable oil and keeping them warm for a few days, so allowing the
aromatic molecules to be absorbed. The resulting liquid is then filtered leaving
the perfumed oil.
Massage: One of the oldest forms of healing which, when used in
Aromatherapy, combines the valuable properties of essential oils with
unconditional physical contact.
Maury, Marguerite: Studied Valnet’s work and applied his research to her
beauty therapy. Along with her physician husband, Madame Maury conducted
much research into the use of essential oils. She is credited with raising the
interest in, and the profile of, Aromatherapy.
Meditative: Promotes the silencing of the mind and slows down the body.
Frankincense oil has a meditative action.
Megallus: An ancient Greek who produced a famous perfume called
‘Megaleion’ which was also used to help heal wounds and reduce
Metabolism: The chemical processes of living organisms. Metabolic reactions
involve the breaking down of molecules to provide energy (catabolism) and
the building of more complex molecules and structures from simpler
molecules (anabolism). It is metabolic reactions, particularly those that create
energy, that keep cells alive.
Milk: Can be used as a carrier for essential oils. Due to its fat content (which
acts as a solvent), it also has a role to play in first aid. It can be drunk should
essential oils accidentally be taken internally, or used as an eyewash should
essential oils be splashed into the eyes. In both cases medical attention must
be sought as soon as possible.
Minerals: Naturally formed inorganic substances which are the constituents of
Molecule: Formed when two or more atoms combine.
Monoterpenes: These are made up of 2 isoprene units (10 carbon atoms)
and are highly volatile. They may irritate the skin and so only weak dilutions
should be used. Limonene (found in most citrus oils) and pinene (found in
pine) are examples of monoterpenes.
Mucolytic: Aids the breaking down of mucus. Both cedarwood (atlas) and
myrrh have a mucolytic action.
Mucous membrane: The tissue that lines the tracts that open to the exterior.
Myalgic encephalomyelitis (ME): Often known as chronic fatigue syndrome
or yuppie flu, ME has no known cause although it is now thought that it could
be an immune system disorder. The unexplained symptoms include extreme
fatigue, a slightly raised temperature, sore throat, tender lymph nodes, muscle
pain, muscle weakness, headaches, sleep disorders and neurological
problems such as memory loss and visual disturbances.
Narcotic: Intoxicating, induces sleep, poisonous in large doses. Clary-sage
has a narcotic action.
Nervine oils: Those that strengthen and tone the nervous system e.g.
lavender, marjoram (sweet), rosemary, thyme (white) and ylang ylang.
Neucleus: Positively charged central portion of an atom, containing protons
Neutron: A particle with no electrical charge found in the nucleus (centre) of
Notes: A means of categorising essential oils according to their volatility and
rate of evaporation. Top note oils are dominated by lighter molecules that are
quick to evaporate and so the first to be smelt, e.g. citrus oils. Middle note oils
consist largely of molecules of moderate volatility and are detected after a
short period of evaporation. These oils are thought to have the most potential
for influencing the body systems, e.g. lavender, geranium and rosemary. Base
note molecules are slow acting and represent the long, lingering impression of
the oil after the top and middle notes have evaporated. Oils dominated by
base notes include sandalwood, rose (cabbage) and frankincense.
Oestrogenic: Aids the production of oestrogen, the sex hormone responsible
for female characteristics. Oils with an oestrogenic action include clary-sage
and fennel (sweet).
Olfactory centre: The part of the brain concerned with the sense of smell.
The olfactory centre is linked by nerves to the hypothalamus.
Olfactory nerve: The nerve of smell that connects the olfactory cells in the
nose to the brain.
Organic compound: Contains carbon and forms the basis for life. All matter
that is living or has once lived will consist of organic compounds.
Oxidation: The process in which a substance reacts with oxygen.
Oxide: A chemical compound found in some essential oils. Oxides are
structured in aliphatic chains and are generally expectorant. The main oxide
that occurs in essential oils is 1,8 cineole (eucalyptus blue gum and tea-tree).
Another is cis-linalool oxide (hyssop). Oxides may irritate the skin and so
combinations high in 1,8 cineole should not be used.
Parasympathetic nervous system: A part of the autonomic nervous system.
The motor nerves originate from cranial nerves (especially the vagus nerve)
and a few of the spinal nerves in the sacral region. The nerve endings release
acetylcholine that decreases the heart rate, breathing rate and blood
pressure, and promotes digestion. This system opposes the sympathetic
Partnership: A means by which a minimum of two people can trade. Liability
is unlimited and partners are jointly and severally liable for the actions/debts of
Parturient: Aiding child birth. Jasmine oil has a parturient action.
Passion flower oil: Latin name: Passiflora incarnata. Produced from the seed
by hot extraction and used as a carrier. An essential oil can be produced
which has anti-inflammatory and narcotic actions.
Peach kernel oil: Latin name: Prunus persica. Produced from the kernel by
cold pressing, it is used as a carrier.
Percolation: A method of extraction in which steam is passed down through
the plant material causing the vaporisation of the tiny, volatile, aromatic
molecules. The vapour is then condensed and the essential oil separated from
the water. This method is otherwise known as hydro-diffusion.
Perfume: A method of use in which essential oils are diluted to 1-3% in either
vodka or a carrier oil and used as a normal perfume.
Peripheral nervous system: Includes all components of the nervous system
except the brain and spinal cord. It includes the system of nerves, originating
at the cranial and spinal nerves, that runs to all organs and peripheral regions
of the body. It also incorporates ganglia situated outside of the brain and
Peristalsis: Waves of muscular movement that pass along tubular organs of
the body. For example, the peristaltic movement of the alimentary canal helps
to force food through.
Perkin, William Henry: Announced the synthesis of coumarin in 1868. With
this came the synthetic copies of perfume and aromatics.
Personal Indemnity Insurance: Insurance against a client claiming that the
treatment given was inappropriate or caused an adverse effect.
Pharmacology: Science of the action of drugs on the body.
Phenol: A chemical compound found in some essential oils. Phenols are
biologically very active. Their atoms are structured in aromatic rings with one
or more hydroxyl group (consisting of hydrogen and oxygen atoms).They
produce a strong, spicy, herbal, medicated aroma. They have powerful
antiseptic and bactericidal effects and are also stimulants. Examples include
eugenol (clove bud), thymol (red thyme) and carvacrol (black pepper).
Phenols need to be treated with caution as many can be highly irritating to the
skin and may toxify the liver. Oils with a high phenol content should be
avoided and others should be used in low dilutions for short periods only.
Photosensitising oils: Oils that increase the skin’s sensitivity to ultraviolet
light and so should not be used before exposure to the sun or a sunbed etc.
The most common photosensitising oils are bergamot, lemon, lime and
Photosynthesis: The process in which green plants trap light energy to
create sugar from carbon dioxide and water. Oxygen is produced as a by-
Physiology: The science of the function of living organisms and the function
of their individual parts.
Pinnate: Leaves arranged on either side of a slender stalk.
Polypus: General name given to a tumour which is attached to the surface by
a stalk. Most polypi are simple, but some may be malignant.
Pomade: Fat that is saturated with aromatic molecules, produced as a result
of methods of extraction such as enfleurage. Pomade is washed in alcohol to
extract the aromatic molecules. The alcohol is then evaporated, leaving the
highly concentrated, highly perfumed absolute.
Pot pourri: Essential oils can be sprinkled onto pot pourri to produce a
pleasant aroma in a room. The scent doesn’t last as long as artificially
produced pot pourri, but the aroma emitted has therapeutic properties.
Pregnancy: The period in which there is a developing child in the womb. All
essential oils must be used in weaker dilutions (just 1-2%) when used on
expectant mothers. Some oils should NEVER be used during pregnancy or
any breast feeding period that may follow, others must be avoided just for the
first three months of pregnancy. Lists of these oils can be found in the 'Safety'
section. The safety data for each oil included in the 'Index of Essential Oils'
will also show if the oil is contra-indicated to pregnancy.
Preventative medicine: Pro-active treatments with the objective of
preventing illness and disease from occurring, rather than treating them once
they are present.
Prophylactic: Tending to prevent disease or infection.
Proton: Positively charged particle found in the nucleus (centre) of an atom.
Psychology: Literally means the study of the mind, but can be defined more
accurately as the scientific study of behaviour and experience.
Public Liability Insurance: Insurance against claims should someone injure
themselves whilst on your premises. It also provides protection should you
cause accidental damage on another’s premises.
Regulator: Helps to balance and regulate (control) the functions of the body.
Oils which are general regulators include palmarosa and rosemary. Ylang
ylang and geranium regulate the production of sebum, melissa regulates the
menstrual cycle and rose (cabbage) is an appetite regulator.
Relaxant: Causes relaxation and calming, aiding the reduction of stress. Oils
with this action include jasmine, lavender and vetivert.
Resin: Gum-like substance produced from the bark of trees or bushes.
Resinoid: Highly perfumed, solid or semi-solid substance produced when
solvents (such as hydrocarbons) are used to extract aromatic molecules from
Rheumatism: A term applied to a group of diseases characterised by
inflammation and pain in the joints, muscles or fibrous tissues.
Rhizome: A plant stem which grows horizontally below ground.
Room spray: A method of use in which essential oils can be sprayed into the
air or on to carpets, curtains and furniture (avoiding good wood). Add 4 drops
of essential oil per 300ml warm water to a new plant sprayer and shake well
before use. The anti-bacterial, anti-viral and antiseptic oils are particularly
suited to this method of use because they help prevent cross-infection.
Rose hip oil: Latin name: Rosa canina/Rosa mollis/Rosa rubignosa. Often
used as a carrier.
Rubefacient: Causes redness of the skin and possible irritation. Oils with a
rubefacient action include black pepper, ginger, pine, thyme (white) and
Sauna: Method of use in which essential oils are vaporised using the heat
source in a sauna. Add 2 drops of essential oil (eucalyptus, tea tree or pine
oils are the most suitable) per 600ml of water and throw it onto the heat
Schizophrenia: Literally means 'split mind' or 'divided self'. It is believed to be
a mental illness, typically characterised by delusions and hallucinations.
Sebum: A complex oily secretion produced by the sebaceous glands (situated
at the upper end of the hair follicle) in the mammalian skin. It prevents the skin
from drying and makes the hair and the skin waterproof. It also contains an
antiseptic ingredient to kill bacteria.
Sedative: Calming, reducing functional activity. Oils with a sedative action
include chamomile (German), cedarwood (atlas), clary-sage, jasmine, may
chang, orange (sweet), marjoram (sweet) and ylang ylang.
Sensitising oils: Oils that can be used infrequently without signs of
intolerance but, with continued use, reactions such as skin inflammations can
occur. They should be diluted to 0.1% before use. A list of sensitising oils can
be found in the 'Safety' section. The safety data for each oil included in the
'Index of Essential Oils' will also show if the oil is a sensitiser.
Sesquiterpenes: Term given to terpenes that contain three isoprene units.
They are heavier than monoterpenes and are prone to oxidation. Examples
include caryophyllene (clove bud) and cadinene (myrrh). There are no known
Shower: To use essential oils whilst showering first wash as usual. Then pour
the essential oil (diluted to 1-3% in a suitable carrier) onto a flannel and rub
briskly all over. Continue to stand under the running water and inhale the
steam. Unperfumed shower gels are good carriers for this method of use.
Sitz bath: Method of use in which 1-2 drops of essential oil diluted in 1
teaspoon of vegetable oil is added to a bowl of warm water large enough to sit
in. Extreme care must be taken as the delicate mucous membranes are easily
Sole Trader: The simplest way in which an individual person can trade. The
advantage of simplicity is balanced by unlimited liability for all actions and
Solvent extraction: The use of solvents such as hydrocarbons and alcohols
to absorb aromatic products from plants. The end products (resinoids,
concretes and absolutes) are not classed as essential oils but are highly
fragrant products with some uses to the Aromatherapist.
Soothing: Calms, makes tranquil. Melissa and sandalwood oils have a
St. John's Wort: Another name for hypericum, used as a carrier.
Steam inhalation: The means by which vaporised essential oils carried in
steam are breathed into the body. This method is particularly good for treating
nose, throat and lung conditions. The direct method of steam inhalation is to
add essential oils to a bowl of hot water, lean over the bowl and inhale the
vapour. Many other methods of use contain an element of steam inhalation,
such as baths, showers and some forms of diffuser.
Steroid: An organic compound that chemically resembles cholesterol. This
group of compounds includes the sex hormones.
Stimulant: Quickens the physiological functions of all of, or a part of, the
body. Oils with a general stimulating action include ginger, niaouli, may chang,
nutmeg, pine and rosemary. Other oils stimulate specific parts of the body e.g.
black pepper stimulates the spleen, cinnamon (leaf) stimulates the cardiac
and respiratory systems and bergamot, eucalyptus (blue gum), lavender,
lemon, tea-tree and vetivert are immuno-stimulants.
Stomachic: Promoting digestion and appetite. Nerol and juniperberry oils
have a stomachic action.
Sudorific: Induces sweating. Hyssop has a sudorific action.
Sympathetic nervous system: A part of the autonomic nervous system. It
increases the heart rate, breathing rate and blood pressure, and slows down
digestion. The motor nerves of this system originate from the spinal nerves in
the thoracic and lumbar regions. The nerve endings release noradrenaline
that creates these ‘fight or flight’ reactions. Sympathetic fibres also trigger the
release of adrenaline.
Synergy: The concept that combined components have a greater effect than
any of the individual components can achieve.
Synthetic: Artificially produced to imitate a natural product.
Tachycardia: Rapid pulse rate.
Terpene: A hydrocarbon commonly found in many essential oils. The carbon
atoms are arranged in isoprene units. Two, three or four isoprene units
combine to form monoterpenes, sesquiterpenes and diterpenes respectively.
Terpenes can react with oxygen and therefore oxidise when exposed to air.
They are generally anti-viral, antiseptic and anti-inflammatory. Examples
include limonene (citrus oils), pinene (pine oil) and chamazulene and
farnesene (German chamomile).
Theophrastus: A Greek (later to become known as the ‘Father of Botany’)
who, around 300 B.C., wrote ‘Enquiry into Plants’. Theophrastus also
discovered that the perfume of jasmine is stronger at night.
Tinnitus: A noise (often ringing) heard in the ear without any external cause.
Tissue/handkerchief: Method of use in which a single drop of essential oil
can be applied neat to a tissue or handkerchief to inhale when required.
Tonic: Strengthens and enlivens the whole of, or specific parts of, the body.
Oils with a general tonic action include basil (European), citronella, cypress
and ylang ylang. Grapefruit oil is a digestive tonic, lemon is a uterine tonic,
and may chang is a digestive and respiratory tonic.
Toning: Aids the state of tension in the muscles. Black pepper and rosemary
oils are toning.
Topical: Local. When oils are applied topically they are applied to the affected
part of the body.
Toxic oils: Oils that can cause toxicity (poisoning) or chronic toxicity if used,
even in low amounts, over a period of time. These oils should therefore be
used with caution and certainly not used for more than a few days at a time.
There is a list of toxic oils in the 'Safety' section. The safety data for each oil
included in the 'Index of Essential Oils' will also show if the oil is toxic.
Uplifting: Able to lift the spirits. Bergamot and may chang are both uplifting.
Valnet, Jean: Medical doctor who used essential oils extensively during the
Second World War. In 1964 he published a book entitled ‘Aromatherapie’
documenting how he had used essential oils to successfully treat both medical
and psychiatric disorders.
Vaso-constrictor: Causes the blood vessels to narrow. Peppermint oil is a
Vaso-dilator: Causes the blood vessels to widen. Marjoram (sweet) oil is a
Viscosity: Degree of stickyness.
Viscous: Sticky or glue-like.
Vitamin: Organic compound necessary in small amounts for the normal
functioning of the body. The deficiency of a vitamin will normally lead to a
Vulnerary: Helps wounds and sores to heal. Myrrh oil has a vulnerary action.
Warming: Creates a degree of heat, either physically or emotionally. Oils with
a warming action include ginger, jasmine and marjoram (sweet).
Wax: One of a group of water insoluble substances that form protective
coverings to leaves, stems, fruits and seed of a plant. They may also occur in
plant cell walls.
Wheatgerm oil: Latin name: Triticum vulgare. An orangey coloured oil, used
as a carrier.
Whitla, William: Published ‘Materia Medica’ in 1882. This book was the first
scientific evaluation of essential oils. It listed 22 official essences including
chamomile, cinnamon, juniper, lavender, lemon, peppermint and rosemary.