Psi

Psi or PSI or Ψ may refer to:

Alphabetic letters

• Psi (letter) (Ψ, ψ), 23rd letter of the Greek alphabet
• Psi (Cyrillic) (Ѱ, ѱ), a letter of the early Cyrillic alphabet, adopted from Greek

In arts and entertainment

In comics

• Psi (comics), a character in DC Comics
• Psi Division, a division in the Judge Dredd and 2000 AD series of comics
• Psi-Force, a comic series
• Psi-Hawk, a comic character
• Psi Lords, a comic series

In music

• PSI (album), an album by Pitchshifter
• Psi Com, a 1980s rock band
• Psi Power, a 1978 song by the UK rock group Hawkwind
• PSI Records, a music record label
• Ψ CMX DVD, a Finnish language video album by the band CMX
• Pitch Shifter Industries, an acronym used by the British band Pitchshifter

Other uses in arts and entertainment

• PSI, the psychic power used by some characters in the EarthBound series
• Psi Corps, in the Babylon 5 fictional universe, the ruling body of Earth's telepaths
• Psi Factor: Chronicles of the Paranormal, a Canadian television series
• Psi-Ops: The Mindgate Conspiracy, a video game in which characters use psychic powers

In mathematics

• Chebyshev function
• Dedekind psi function
• Digamma function
• Polygamma functions
• Stream function, in two-dimensional flows
• Tangential angle of a curve
• Probability of ultimate ruin, in ruin theory

In parapsychology

• Psi (parapsychology), psychic or paranormal phenomena
• Psi hit, a parapsychological experimentation term
• Paranormal Site Investigators, in the UK

In science and technology

• Pounds per square inch, a unit of pressure

In biology and medicine

• PSI (prion), an infectious protein in yeast
• Pandemic severity index, by the US Centers for Disease Control and Prevention
• Photosystem I, a protein complex involved in photosynthesis
• Pneumonia severity index
• Protein Structure Initiative, a structural genomics initiative of the U.S. NIGMS

In computing

• Psi (instant messaging client), an XMPP client program
• Potentially Shippable Increment, in the Scrum software development methodology
• Program-specific information, part of the MPEG transport stream protocol

In physics and chemistry

• PSI (computational chemistry), software
• J/psi meson, a subatomic particle
• Porous silicon, a material
• Water potential, denoted Ψ, in physical chemistry, the potential energy of a water solution relative to pure water
• Wave function, denoted ψ, in quantum mechanics

In psychology

• Psychology or psychologist, denoted Ψ, used in the logo of various psychological associations
• Psi Chi, the National Honor Society in Psychology
• Psi-Theory, a theory about the human mind, a cognitive architecture
• Psychiatric Solutions, Inc., a corporation that owns psychiatric hospitals

Other uses in science and technology

• Pollutant Standards Index, an air pollution measure
• "Yaw" angle, one of the Euler angles, denoted ψ in aerospace engineering

Organizations

In education

• Pechersk School International, in Kiev, Ukraine
• Professional Skills Institute, a private university in Toledo, Ohio

In government and politics

• Italian Socialist Party (Partito Socialista Italiano)
• Italian Socialist Party (2007)
• Partai Sosialis Indonesia ("Indonesian Socialist Party")
• Proliferation Security Initiative, an international effort to interdict transfer of banned weapons and weapons technology
• Public Sector Information, as in:
  • The European Union Directive on the re-use of public sector information (PSI directive), adopted in November 2003
  • The United Kingdom's Office of Public Sector Information (OPSI), formerly Her Majesty's Stationery Office (HMSO)
• United States Senate Homeland Security Permanent Subcommittee on Investigations, a sub-committee of the U.S. Senate

Other organizations

• Paranormal Site Investigators, in the UK
• Paul Scherrer Institute, a research institute in Villigen, Switzerland
• Poetry Slam, Inc.
• Policy Studies Institute, a UK research organization
• Population Services International, a nonprofit global health organization
• Professors for a Strong Israel, a right-wing group of academics in Israel
• Psychiatric Solutions, Inc., a corporation that owns psychiatric hospitals
• Public Services International, a global union federation of public sector trade unions
• Statisticians in the Pharmaceutical Industry
• Prudential Securities Incorporated, a financial services company

Other uses

• Permanent staff instructor, in the British Army
• Private sector involvement, in sovereign-debt restructuring deals
• PSI-20, a stock market index of companies that trade on Euronext Lisbon, the main stock exchange of Portugal
• Psi Islands, in the Melchior Islands, Antarctica
• Presentence investigation report, an investigation into the history of person convicted of a crime
• Pre-shipment inspection, a method of quality control

See also

• Psy (disambiguation)
• Ps1 (disambiguation)