The Collaborative International Dictionary
Chromous
Chromous \Chro"mous\, a. Of, pertaining to, or derived from, chromium, when this element has a valence lower than that in chromic compounds.
Chromous acid, a bluish gray powder, CrO.OH, of weak acid properties and regard as an acid.
Wiktionary
chromous
a. (context chemistry English) of, relating to, or containing chromium, especially in oxidation state 2