The Collaborative International Dictionary of English v.0.48:
itaconic acid \it`a*con"ic ac"id\, n. (Chem.) The unsaturated dicarboxylic acid CH2=C(COOH)CH2.COOH, also called methylenesuccynic acid and propylene dicarboxylic acid. [PJC]WordNet (r) 3.0 (2006):
itaconic acid n 1: a crystalline carboxylic acid; occurs in some fermentations of sugars