Essential oils

Main Entry: essential oil
Function: noun
: any of a large class of volatile odoriferous oils of vegetable origin that give plants their characteristic odors and oftenother properties, that are obtained from various parts of the plants (as flowers, leaves, or bark) by steam distillation, expression, or extraction, that are usually mixtures of compounds (as aldehydesor esters), and that are used often in the form of essences in perfumes, flavorings, and pharmaceutical preparations called also ethereal oil, volatile oil; —compare FATTY OIL, FIXED OIL

essential oil n.
A volatile oil, usually having the characteristic odor or flavor of the plant from which it is obtained, used to make perfumes and flavorings.