a. (Chem.) Pertaining to, or containing, vanadium; specifically, designating those compounds in which vanadium has a lower valence as contrasted with the vanadic compounds; as, vanadious acid. Usually written vanadous. [ Sometimes written also vanadous. ] [ 1913 Webster ]

n. [ NL., fr. Icel. Vanadīs, a surname of the Scandinavian goddess Freya. ] (Chem.) A rare element of the nitrogen-phosphorus group, found combined, in vanadates, in certain minerals, and reduced as an infusible, grayish-white metallic powder. It is intermediate between the metals and the non-metals, having both basic and acid properties. Symbol V (or Vd, rarely). Atomic weight 50.94 (C12=12.000). [ 1913 Webster +PJC ]

(Chem.) A yellow pigment consisting of a compound of vanadium. [ Webster 1913 Suppl. ]