fatty acid

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of a large group of monoprotic acids, especially those found in animal and vegetable fats and oils, having the general formula C_nH_2n+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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun chemistry Any of a class of aliphatic carboxylic acids, of general formula CnH2n+1COOH, that occur combined with glycerol as animal or vegetable oils and fats. Only those with an even number of carbon atoms are normally found in natural fats.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun 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