Pronunciation: (al'dôl, -dol),[key] —n.Chem. 1. Also called acetaldol. a colorless, syrupy, water-soluble liquid, C4H8O2, formed by the condensation of acetaldehyde: used chiefly in the manufacture of rubber vulcanizers and accelerators, and in perfumery.
2. any of a class of compounds containing both an alcohol and an aldehyde functional group, formed by a condensation reaction between aldehyde or ketone molecules.