pEnglishOxford New American Dictionaryp /pē, pi / ▸ abbreviation 1 page: see p 784. 2 (p-) [in combination] Chemistry para-: p -xylene. 3 British penny or pence: a 5p coin. 4 Music piano (softly). 5 [in combination] (in units of measurement) pico- (10-12): a 220 pf capacitor. 6 Chemistry denoting electrons and orbitals possessing one unit of angular momentum: p-electrons. [from principal, originally applied to lines in atomic spectra.] ▸ symbol 1 Physics pressure: pV = nRT. 2 Statistics probability: this difference was significant (p = 0.0008).