Aromatherapy A-Z Glossary




Products, not strictly essential oils, obtained through chemical solvent extraction.


The art and science of using essential oils extracted from botanicals to relax, balance and rejuvenate the body, mind and spirit.

Aromatherapy Benefit

The emotional or physical effect evoked by aromatic essential oils. Examples include balancing, energizing, rejuvenating, cleansing, deodorizing and purifying.


Many plants contain furocoumarins such as bergaptene, which are known photosensitizers. Bergaptene is a naturally occurring component of bergamot essential oil. When bergamot oil is applied, the skin can become very sensitive to ultraviolet light. Severity of the reaction depends on length of exposure and individual sensitivity. Mild cases can be a reddening of the skin while severe cases can result in acute lesions known as bullock dermatitis. The dermatitis will resolve itself in a few weeks; however the accompanying hyperpigmentation (brown spots on the skin) can take months or years to fully disappear. Aura Cacia offers a bergaptene-free version of bergamot essential oil. There is not evidence to indicate that removing the bergaptene in anyway affects the aromatherapy benefit of the essential oil and we recommend using bergaptene-free bergamot whenever possible.

Carrier Oil

A vegetable oil base in which essential oils are diluted to create massage blends and body care products. Examples include sweet almond, apricot kernel, jojoba and grapeseed.

Cold Press Extraction

 (See "Expression")


An aromatherapy accessory used to gently disperse essential oils into the air for olfactory benefit.


Diffusion is the spontaneous movement of liquid, gas, or solid particles from an area of high concentration to low concentration. For example, uncapping a bottle of essential oil produces diffusion as the volatile constituents move from the bottle (an area of high concentration) into the environment (an area of low concentration) without being acted upon by heat or pressure. This could also be referred as spontaneous evaporation. Technically, all of the apparatuses used in aromatherapy vaporize or volatilize essential oils because they are acted upon by heat, and/or pressure, to produce fine separated particles or vapor.


A product of distillation. For example, lavender oil is the distillate of the fresh, blooming lavender plant.


The primary method of producing essential oils is through steam distillation. Distillation is an age-old process. While the crude still of the past (almost identical to the simple country "moonshine" still) is now often replaced with modern, stainless steel versions, the process is still basically unchanged. Water is heated to boiling and steam passes through fresh plant material stacked on a rack above the boiling water, causing the cell walls of the plant to break down and release the essential oil. The water and essential oil vapor then pass through a cooler that condenses the steam and the oil into a liquid. The liquid is collected and the oil separates from the water. Most oils are lighter than water and thus collect on the surface of the water where they are siphoned off. Oils heavier than water sink to the bottom of the collector where they are removed. Some stills use "direct," or "water" distillation where the plant material is mixed with the boiling water with the same effect.


Age-old method of extracting essential oils using odorless fats and oils to absorb the oil from the plant material.

Essential Oil

The highly concentrated, volatile, aromatic essences of plants. Information on specific essential oils can be found in the Essential Oil Directory.


Method of obtaining essential oil from plant material, such as citrus fruit peel. The complete oil is physically forced from the plant material. Also known as cold press extraction.

Extraction Method

The method by which essential oils are separated from the plant. Common extraction methods include distillation, expression and solvent extraction.


A fixative is a plant or animal substance of low volatility that serves to draw together and hold the fragrances of other materials. It may be in the form of a liquid, such as an essential oil or fragrance that will slow the evaporation process and preserve the aromatic sensation of the blend, or it may be in the form of a botanical that will absorb and hold the various aromas. Using a fixative will create a more distinct and longer lasting product. Orris root, amyris, calamus root, angelica root, and vetiver root are a few commonly used fixatives.

Food Grade

Considered safe for use in food by the Food and Drug Administration.


Aroma. Products labeled as fragrances are not the same as essential oils. Fragrances are derived by synthetic means, while essential oils are derived from plant bontanicals. 

Herbal, Herbalism

Pertaining to botanicals and living plants.


Hydrosol is the name for the water left after a steam or water distillation of an essential oil. It is mainly water with only a very small amount of water soluable plant constiutents.


Unable to be dissolved in a liquid such as water.

Massage Therapy

A hands-on therapy in which essential oils are applied to the body for emotional and physical benefits.


A "neat" drop refers to a drop of liquid that is unmixed, or undiluted. When referencing an aromatherapy recipe for example, a neat drop of lavender essential oil is a drop of oil taken directly from the bottle, and added to the recipe.


Of, relating to or connected with the sense of smell.

Patch test

Some people have reactions to certain oils and cannot use them. To test an essential oil you have not used before, do a patch test by adding 1 drop of oil to 1/2 tsp. vegetable oil and apply to the inside of the arm. Leave on for 24 hours, and if any redness or itching develops, don't use the oil.


A fragrant mixture of dried herbs and flowers. Usually scented with synthetic fragrance oils.

Prussic Acid

Many fruits, nuts, seeds, legumes and pasture type grasses that are a daily part of human and animal diets contain naturally occurring cyanogenic glycosides such as amygdalin, which when ingested, break down into three substances; sugar, cyanide (prussic acid), and benzaldehyde. Benzaldehyde is the substance used as a flavoring and fragrance material. It has an almond or cherry taste, and an almond-like aroma. The kernel (also referred to as the pit or stone) of almonds, apricots, plums, peaches, contains the prussic acid, although the fruit is entirely unaffected. The kernels of these fruits are used to make almond essential oil. The oil produced from these pits intended for food use is treated to remove the prussic acid, and is designated as FFPA (free from prussic acid). The Code of Federal Regulations (21 CFR 582.20) states that prussic acid-free bitter almond oil is considered GRAS (generally recognized as safe) as a food flavoring.


Substances for external application that cause redness of the skin through dilation of the capillaries, which allows for increased blood circulation, resulting in a warming sensation.

Sebaceous Glands

Present in the dermis. Open to the surface at pores located in the epidermis. Produces sebum (oil).


The oily substance produced by the sebaceous glands which function to lubricate the skin and seal moisture into the cells. The level of sebum production determines whether your skin is normal, dry or oily.

Single Note

An essential oil sourced from a single botanical without any other ingredients.


Able to be dissolved in a liquid such as water.


A characteristic in which the total effect is more effective than the individual parts.


An artificially produced substance designed to imitate that which occurs naturally.


Pertaining to the thickness or thinness of a liquid.


The rate of evaporation or oxidation of an essential oil.