Source : Webster's Revised Unabridged Dictionary (1913)

Sulphacid \Sulph*ac"id\, n. [Sulpho- + acid.] (Chem.)
   An acid in which, to a greater or less extent, sulphur plays
   a part analogous to that of oxygen in an oxyacid; thus,
   thiosulphuric and sulpharsenic acids are sulphacids; --
   called also {sulphoacid}. See the Note under {Acid}, n., 2.