The Collaborative International Dictionary of English v.0.48:
Bitartrate \Bi*tar"trate\, n. (Chem.) A salt of tartaric acid in which the base replaces but half the acid hydrogen; an acid tartrate, as cream of tartar. [1913 Webster]WordNet (r) 3.0 (2006):
bitartrate n 1: an acid tartrate; a hydrogen tartrate