PS

PS in letters stands for post scriptum, or postscript.

ps

• .ps, the Palestinian Internet domain extension or top-level domain (ccTLD)
• Pashto language, ISO 639 alpha-2 language code
• picosecond, an SI unit of time equivalent to 10^-12 of a second, standard abbreviation ps (uncapitalized)
• ps (Unix), an application that displays statistics on running processes
• the Greek letter psi. In English, "ps" may be regarded as a diagraph for /s/, as the "p" is silent
• ps (Trading) may refer to put spread
• P.S., abbreviation for "post scriptum", a Latin expression meaning "after writing"

pS

• picosiemens, an SI unit of electric conductance; see: pico- and siemens (unit)

Ps

• Peta second, an SI unit of time equivalent to 10¹⁵ seconds; see: Peta (prefix) and second
• Psalms, a book in the Tanakh or Christian Bible
• Positronium, pseudo-chemical symbol

PS

• Police Sergeant
• Police station
• Polystyrene, a common type of plastic
• Paddle steamer
• Palau, FIPS PUB 10-4 territory code
• Palestinian territories, ISO 3166 country code
• Parametric Stereo
• Pferdestärke (German for "horse power"), a unit of power commonly used in Europe, South America and Japan, especially by the automotive and motorcycle industry
• Postscript, a message appended to a letter after the writer's signature
• Professional services, especially those provided by a vendor
• Proton Synchrotron
• Public school, e.g., P.S. 31
• Ukraine International Airlines, IATA airline designator
• Porous silicon
• Pulmonary Stenosis
• Power steering
• Power supply
• Phosphatidylserine, a phospholipid
• Plastic surgery

In computers:

• Adobe Photoshop, a graphics editor and creator by Adobe
• PostScript, a page description language
• Program stream, a MPEG-2 container format
• Windows PowerShell, a Microsoft application
• Pixel shader

In education:

• pre-school

In entertainment, music and literature:

• Priory of Sion, Prieuré de Sion, mentioned in The Da Vinci Code
• PS Classics, a record label
• P.S., a 2004 film
• P.S. I Love You (film), a 2007 film
• P.S. (A Toad Retrospective), a compilation album of music by Toad the Wet Sprocket
• P.S. (album), a compilation album of film music by Goran Bregovic
• "PS," a song by The Books from the album The Lemon of Pink
• Harry Potter and the Philosopher's Stone or Harry Potter and the Philosopher's Stone (film)

Political parties:

• Parti Socialiste
• French Socialist Party
• Belgian Francophone Socialist Party, see: Socialist Party (francophone Belgium)
• Social Democratic Party of Switzerland
• Partido Socialista, Portuguese for Socialist Party (Portugal)
• Partido Socialista de Chile, Spanish for Socialist Party (Chile)
• Partidul Socialist [din România], Romanian for Socialist Party of Romania

Companies:

• PeopleSupport, a Los Angeles-based business process outsourcing company
• Pyramid scheme, tricking people into making money for a company/individual through obligations and false pretenses of mutual gain

In video games:

• PlayStation, a TV game console by Sony
• See also:
• PSone
• PlayStation 2
• PlayStation 3

• Phantasy Star, series of RPG games by SEGA
• Planetside, a MMOFPS by Sony