Vanadious a. : 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.

Example:


Taxonomy
vanadium, compounds, element, vanadium pentoxide, vanadium compounds, vanadium oxide, metal, oxidation states, isotopes, steel, titanium, vanadium steel, chemistry, vanadium alloys, oxide, element vanadium, steel alloys, Del Río.

Defination from the web:
... of vanadium metal proved difficult. In 1831, Berzelius reported the production of the metal, but Henry Enfield Roscoe showed that Berzelius had in fact produced the nitride, vanadium nitride (VN) ...