Wiktionary
phosphine oxide
n. (context chemistry English) any compound having the general formula R3P=O <=> R3P+O-
Wikipedia
Phosphine oxide
Phosphine oxides are phosphorus compounds with the formula OPX. When X = alkyl or aryl, these are organophosphine oxides. Triphenylphosphine oxide is an example. An inorganic phosphine oxide is phosphoryl chloride (POCl). Such compounds are thermally stable, decomposing only above 450 °C. Phosphoryl refers to a functional group drawn with a phosphorus-oxygen double bond.