- fatty acid - any of a class of aliphatic monocarboxylic acids that form part of a lipid molecule and can be derived from fat by hydrolysis; fatty acids are simple molecules built around a series of carbon atoms linked together in a chain of 12 to 22 carbon atoms
--1 is a kind of carboxylic acid
--1 has particulars: saturated fatty acid; unsaturated fatty acid; trans fatty acid