PN

PN may refer to:873881272

Astronomy

• Planetary nebula. The 1992 Version of the Strasbourg-ESO Catalog of Galactic Planetary Nebulae uses "PN" and "PNG" object prefixes.^[1]

Biology

• Parenteral nutrition
• Phylogenetic nomenclature, an approach to naming groups of living thingsfhiml

Business and economics

• Pacific National, a rail freight company in Australia
• Patriotic Nigras, a powerful griefing group in Second Life
• Payment Notification, common procedural step in e-commerce payments
• Pennsylvania Northeastern Railroad, reporting mark
• Promissory note, a contract where one party makes an unconditional promise in writing to pay a sum of money to another

Culture and entertainment

• Purple Noon, a 1960 film

Electronics

• p-n junction, a type of junction in electronics

Geography

• Pitcairn Islands, ISO 3166-1 country code
  • .pn, the country code top level domain (ccTLD) for Pitcairn Islands
• Palmerston North, a city in New Zealand

Linguistics

• Proper noun, a linguistic term for the name of an entity

Mathematics

• Polish notation, a prefix notation proposed by Jan Łukasiewicz
• Pseudorandom number sequence

In mathematics, the combination of the letters P and n may refer to:

• Path graph of size $n$, denoted by $P_n$
• Polynomial vector spaces, denoted by $\mathbb{P}_n$

Navies

• Pakistan Navy
• Peruvian Navy
• Philippine Navy
• Portuguese Navy

People

• Pascal Nouma, a former player of Beşiktaş J.K.
• Pat Nixon, a former First Lady of the United States

Physics

• Post-Newtonian expansion, an approximation of General Relativity
• Proportional navigation, a concept in missile guidance systems
• pseudonoise aka pseudorandom noise, a deterministic sequence of pulses used in spread spectrum communication and rangefinding

Political Parties

• National Renaissance Front, Partidul Naţiunii, a political party in Romania
• Partit Nazzjonalista, a political party in Malta

Software

• Programmer's Notepad, a text editor

Other

• Part number
• Participatory notes
• Petri Net
• Pottery Neolithic (see Neolithic)
• Particle number in air-quality measurement

References

1. http://heasarc.gsfc.nasa.gov/W3Browse/nebula-catalog/plnebulae.html