Osmious
Pronunciation : Os"mi*ous
Part of Speech : a.
Definition : Defn: Denoting those compounds of osmium in which the element has a valence relatively lower than in the osmic compounds; as, osmious chloride. [Written also osmous.] Osmious acid (Chem.), an acid derived from osmium, analogous to sulphurous acid, and forming unstable salts. It is a brown amorphous substance.
(Chem.)
Source : Webster's Unabridged Dictionary, 1913