Protosulphide
Pronunciation : Pro`to*sul"phide
Part of Speech : n.
Etymology : [Proto- + sulphide.] (Chem.)
Definition : Defn: That one of a series of sulphides of any element which has the lowest proportion of sulphur; a sulphide with but one atom of sulphur in the molecule.
Source : Webster's Unabridged Dictionary, 1913