AskDefine | Define psi

Dictionary Definition



1 a unit of pressure [syn: pounds per square inch]
2 the 23rd letter of the Greek alphabet

User Contributed Dictionary


Alternative spellings


sc=Grek, the name for the twenty-third letter of the alphabet (Ψ, ψ).


  • In contexts where confusion might arise with the Greek letter xi, which also has sī, , /saI/ as a possible pronunciation, the pronunciation of the "p" in psi is preferable.
  • Rhymes with: -aɪ


  1. The twenty-third letter of Classical and Modern Greek and the twenty-fourth letter of Old and Ancient Greek.
  2. uncountable parapsychology A form of psychic energy.
    1993, ‘Come, lad,’ he said. ‘We will take tea together and speak of the noumenon, the psi and other more heterogenous phenomena.’ — Will Self, My Idea of Fun
  • Letter of the Greek alphabet: '''Ψ ψ
    • Previous: Χ
    • Next: Ω


Greek letter
  • French: psi
  • Greek, Modern: ψι
  • Interlingua: psi
  • Italian: psi
  • Portuguese: psi
  • Russian: пси
psychic energy
  1. Pounds per square inch (an imperial unit of pressure)



Extensive Definition

As a word

As a Greek letter

  • J/ψ particle, a subatomic particle
  • Wavefunction in Quantum Mechanics, ψ
  • In physical chemistry, Ψ represents water potential, the potential energy of a water solution relative to pure water
  • Ψ stands for psychology and psychologist, often used in the logo of various psychological associations
  • ΨΧ (Psi Chi), National Honor Society in Psychology

In mathematics

As an abbreviation


PSI can be an abbreviation for:


In comics

In music

  • Psi Power, a 1978 song by the UK rock group Hawkwind
  • Psi Com, a 1980s rock band

In video games

  • In the EarthBound series, the main characters use psychic abilities known as PSI pronounced PK. Examples of these powers are PSI(PK) Fire and PSI(PK)Freeze.
psi in Czech: Psi
psi in Danish: Psi
psi in German: Psi (Begriffsklärung)
psi in Spanish: Psi
psi in Esperanto: PSI
psi in French: Psi
psi in Korean: PSI
psi in Italian: PSI
psi in Dutch: Psi
psi in Japanese: PSI
psi in Polish: Psi
psi in Portuguese: Psi
psi in Russian: Psi (значения)
psi in Finnish: PSI
psi in Swedish: Psi (olika betydelser)
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