An
essential oil is a concentrated
hydrophobic liquid containing volatile
aroma compounds from plants. Essential oils are also known as
volatile oils,
ethereal oils,
aetherolea, or simply as the
oil of the plant from which they were extracted, such as
oil of clove. An
oil is "essential" in the sense that it contains the "essence of" the plant's fragrance—the characteristic fragrance of the plant from which it is derived. The term essential used here does not mean indispensable as with the terms
essential amino acid or
essential fatty acid which are so called since they are nutritionally required by a given living organism.