Phosphorous \Phos"phor*ous\ (f[o^]s"f[o^]r*[u^]s), a. [Cf. F.
phosphoreux.] (Chem.)
Of or pertaining to phosphorus; resembling or containing
phosphorus; specifically, designating those compounds in
which phosphorus has a lower valence as contrasted with
{phosphoric} compounds; as, phosphorous acid, {H3PO3}.
[1913 Webster]