Noun | 1. | 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 carboxylic acid - an organic acid characterized by one or more carboxyl groups saturated fatty acid - a fatty acid whose carbon chain cannot absorb any more hydrogen atoms; found chiefly in animal fats unsaturated fatty acid - a fatty acid whose carbon chain can absorb additional hydrogen atoms trans fatty acid - a fatty acid that has been produced by hydrogenating an unsaturated fatty acid (and so changing its shape); found in processed foods such as margarine and fried foods and puddings and commercially baked goods and partially hydrogenated vegetable oils |