The Collaborative International Dictionary of English v.0.48:
Vanadate \Van"a*date\, n. [Cf. F. vanadate.] (Chem.) A salt of vanadic acid. [Formerly also vanadiate.] [1913 Webster]WordNet (r) 3.0 (2006):
vanadate n 1: a salt or ester of vanadic acid; an anion containing pentavalent vanadium