D defs.my
Entry 1 sense Webster, 1913

Manganous

· Man·ga·nous · IPA
01 a. Of, pertaining to, designating, those compounds of manganese in which the element has a lower valence as contrasted with manganic compounds…
  1. 1.
    Of, pertaining to, designating, those compounds of manganese in which the element has a lower valence as contrasted with manganic compounds; as, manganous oxide.(Chem.)
Phrases & compounds
Manganous acid — a hypothetical compound analogous to sulphurous acid, and forming the so-called manganites.