(chemistry) a chemical element (symbol P) with an atomic number of 15, that exists in several allotropic forms. / (obsolete) any substance exhibiting phosphorescence; a phosphor

A name sometimes used for Hesperus, the personification in Greek mythology of the planet Venus.

(physics) The only stable isotope of phosphorus, ³¹₁₅P, having fifteen protons and sixteen neutrons

(chemistry, obsolete) tetraphosphorus trisulphide

(inorganic chemistry) A purple crystalline allotrope of phosphorus.

(chemistry) an inorganic polymer, of empirical formula PON, used as a flame retardant etc

Synonym of white phosphorus

(inorganic chemistry) A form of phosphorus that can be produced by day-long annealing of red phosphorus above 550 °C.

(chemistry) The least reactive of the allotropes of phosphorus; it has no significant commercial use.

(inorganic chemistry) the compound, P₂O₅, formed by the spontaneous combustion of white phosphorus in air; it reacts violently with water to form phosphoric acid and is used as a powerful desiccating agent