essential oils, volatile oils that occur in plants and in general give to the plants their characteristic odors, flavors, or other such properties. Essential oils are found in various parts of the plant body (in the seeds, flowers, bark, or leaves) and are also concentrated in certain special cells or groups of cells (glands). Because of their properties, they are widely used in perfumes, flavorings, and medicines. Their chemical composition differs: A great many, for example, are principally terpenes, compounds of carbon and hydrogen. Others contain aldehydes, ketones, or phenols. Oxygen, sulfur, and nitrogen are present in compounds in others. In general, they are complex mixtures. They are obtained from the plant in various ways, depending upon the nature of the part in which they occur—by compression, by distillation with steam, by dissolving the oils out (extraction) or absorbing them, and by pressure and maceration. Among the plants notable for their essential oils are members of the following plant families: carrot (e.g., anise, dill, angelica), ginger (cardamom), heath (wintergreen), laurel (cinnamon and camphor), mint (pennyroyal, peppermint, spearmint, thyme), myrtle (clove and eucalyptus), olive (jasmine and lilac), orchid (vanilla), pulse (acacia and sweet pea), rose (attar of roses and almond), and rue (lemon and other citrus plants).

Any of a class of highly volatile (readily evaporating) organic compounds found in plants and usually named for them (e.g., rose oil, peppermint oil). They have been known and traded since ancient times. Many essential oils contain isoprenoids. Some, such as oil of wintergreen (methyl salicylate) and orange oil (math.d-limonene), have one predominant component, but most have dozens or hundreds. Trace components impart an oil's characteristic odour, which synthetic or blended oils can rarely duplicate. Essential oils have three primary commercial uses: as odorants in perfumes, soaps, detergents, and other products; as flavours in baked goods, candies, soft drinks, and many other foods; and as pharmaceuticals, in dental products and many medicines (see aromatherapy).

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