psi

Look up psi or PSI in Wiktionary, the free dictionary.

Psi or PSI may refer to:

As a letter or word

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

In science and technology

• Psi (instant messaging client), a popular XMPP client program
• Psi Chi, the National Honor Society in Psychology
• J/ψ meson, a subatomic particle
• Psi-Theory, a theory about the human mind, a cognitive architecture
• Psychology or psychologist, denoted Ψ, used in the logo of various psychological associations
• 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 mathematics

• Tangential angle of a curve, denoted ψ
• ψ may denote several mathematical functions, including:
  • Chebyshev function
  • Dedekind psi function
  • Digamma function
  • Polygamma functions
  • Stream function, in two-dimensional flows

In entertainment

• Psi (comics), a character in DC Comics
• Psi Com, a 1980s rock band
• Psi Corps, in the Babylon 5 fictional universe, the ruling body of Earth's telepaths
• Psi Division, a division in the Judge Dredd and 2000 AD series of comics
• Psi Factor: Chronicles of the Paranormal, a Canadian television series
• Psi-Force, a comic series
• Psi-Hawk, a comic character
• Psi Lords, a comic series
• Psi-Ops: The Mindgate Conspiracy, a video game in which characters use psychic powers
• Psi Power, a 1978 song by the UK rock group Hawkwind
• PSI, the ability used by characters from the EarthBound series
• PSI (album), an album by Pitchshifter

Other uses

• Psi (parapsychology)
• Psi hit, a parapsychological experimentation term

As an abbreviation

In science and technology

• Pounds per square inch, a unit of pressure
• PSI (computational chemistry), software
• 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
• Pollutant Standards Index, an air pollution measure
• Porous silicon, a material
• Program Specific Information, part of the MPEG transport stream protocol
• Protein Structure Initiative, a structural genomics initiative of the U.S. NIGMS

Organizations

• Paranormal Site Investigators, an education and research charity in the UK
• Paul Scherrer Institute in Villigen, Switzerland
• Population Services International, an international healthcare NGO based in Washington DC
• Professional Secretaries International
• Professors for a Strong Israel, a right-wing group of academics in Israel
• Public Services International, a global union federation of public sector trade unions
• Statisticians in the Pharmaceutical Industry

In politics and government

• Partai Sosialis Indonesia ("Indonesian Socialist Party")
• Italian Socialist Party (Partito Socialista Italiano)
• United States Senate Homeland Security Permanent Subcommittee on Investigations, a sub-committee of the U.S. Senate
• Proliferation Security Initiative, an international effort to interdict transfer of banned weapons and weapons technology

Other uses

• PSI Records, a music record label
• Pechersk School International, in Kiev, Ukraine
• Permanent Staff Instructor, in the British Army
• PSI-20, a stock market index of companies that trade on Euronext Lisbon, the main stock exchange of Portugal
• Presentence investigation, in law, an investigation into the history of person convicted of a crime, before sentencing
• Pre-shipment inspection, a method of quality control
• Professional Skills Institute, a private university in Toledo, Ohio
• Pitch Shifter Industries, an acronym used by the British band Pitchshifter

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