phosphorous Definition

of, relating to, or containing phosphorus especially with a valence lower than in phosphoric compounds

a phosphorescent substance or body; especially : one that shines or glows in the dark

a nonmetallic element of the nitrogen family with atomic number 15 that occurs widely in combination especially as phosphates, that is essential for life in all known organisms, and that is used especially in fertilizers and organophosphorus compounds

a deliquescent crystalline acid H3PO3 used especially as a reducing agent and in making phosphites