any of a class of lipids consisting of various saturated or unsaturated, monobasic organic acids, generally R·COOH, usually in a straight chain: they occur naturally in the form of glycerol esters in animal or vegetable fats and oils
See fatty acid in American Heritage Dictionary 4
noun
Any of a large group of monobasic acids, especially those found in animal and vegetable fats and oils, having the general formula CnH2n+1COOH. Characteristically made up of saturated or unsaturated aliphatic compounds with an even number of carbon atoms, this group of acids includes palmitic, stearic, and oleic acids.