Betaine \Be"ta*ine\, n. [From beta, generic name of the beet.] (Chem.) A nitrogenous base, {C5H11NO2}, produced artificially, and also occurring naturally in beet-root molasses and its residues, from which it is extracted as a white crystalline substance; -- called also {lycine} and {oxyneurine}. It has a sweetish taste. [1913 Webster]