What is "caffeic acid"

Caffeic \Caf*fe"ic\, a. [See Coffee.] (Chem.) Pertaining to, or obtained from, coffee.

Caffeic acid, an acid obtained from coffee tannin, as a yellow crystalline substance, C9H8O4.

n. (context organic compound English) The phenolic carboxylic acid ''3-(3,4-dihydroxyphenyl 2-propenoic acid'' that is an intermediate in the biosynthesis of lignin

Caffeic acid is an organic compound that is classified as hydroxycinnamic acid. This yellow solid consists of both phenolic and acrylic functional groups. It is found in all plants because it is a key intermediate in the biosynthesis of lignin, one of the principal components of plant biomass and its residues.