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
string quartet: an instrumental quartet with 2 violins and a viola and a cello