PN may refer to: Arts and entertainment Purple Noon, a 1960 film Patriotic Nigras, a griefing group in the game Second Life Business and economics Pacific National, a rail freight company in Australia Participatory notes, issued to unregistered overseas investors in Indian stock markets Pennsylvania Northeastern Railroad (reporting mark PN) Promissory note, a contract where one party makes an unconditional promise in writing to pay a sum of money to another West Air (China) (IATA airline code PN) Organizations Navies Pakistan Navy Peruvian Navy Philippine Navy Portuguese Navy Political parties National Renaissance Front, Partidul Naţiunii, a political party in Romania Partit Nazzjonalista, a political party in Malta Perikatan Nasional, a political coalition in Malaysia Partido Nacional (Uruguay), a political party in Uruguay Places Penang Pitcairn Islands (ISO 3166-1 country code) Palmerston North, a city in New Zealand Province of Pordenone, a province in the autonomous region of Friuli Venezia Giulia in Italy Science, technology, and mathematics Biology Parenteral nutrition Phylogenetic nomenclature, an approach to naming groups of living things Electronics and computing .pn, the country code top level domain (ccTLD) for Pitcairn Islands p–n junction, a type of junction in electronics Mathematics Path graph of size , denoted by Petri net, one of several mathematical modeling languages for the description of distributed systems Polish notation, a prefix notation proposed by Jan Łukasiewicz Polynomial vector spaces, denoted by Pseudorandom number sequence Other uses in science and technology Part number, an identifier of a particular part design used in a particular industry Particle number, in air-quality measurement petanewton, a quadrillion newtons Planetary nebula, in astronomy Post-Newtonian expansion, an approximation of General Relativity Proportional navigation, a concept in missile guidance systems Pseudorandom noise, a deterministic sequence of pulses used in spread spectrum communication and rangefinding Phosphorus mononitride (PN), an inorganic compound found in space Other uses Pottery Neolithic Proper noun, a linguistic term for the name of an entity Public News, an alternative newspaper in Houston (1982-1998)