The hypophosphite ion is H2PO2−, hypophosphorous acid minus one hydrogen ion. Hypophosphites are the compounds containing this ion, with phosphorus in oxidation state +1, or similar covalent ones. Two hydrogens are attached directly to the phosphorus atom. The IUPAC (mostly organic) name for the same ion is phosphinate. This is virtually not use...
• (n.) A salt of hypophosphorous acid.
Hy`po·phos'phite noun (Chemistry) A salt of hypophosphorous acid. 
a salt of hypophosphorous acid, as sodium hypophosphite, NaHPO.