What is Psi?
'''Psi''' could mean: ==As a word== * [[Psi (Cyrillic)]] (Ѱ, ѱ), a letter of the early Cyrillic alphabet, adopted from Greek * [[Psi (letter)|Psi]] (Ψ, ψ) a letter of the Greek alphabet * [[Psi (comics)]], a character in DC Comics * [[Psi (instant messaging client)]], a popular Jabber client program * [[Psi (parapsychology)]], psychic or paranormal phenomena ==As a Greek letter== * [[J particle|J/ψ particle]], a subatomic particle * [[Wavefunction]] in [[Quantum Mechanics]], ψ * In [[mathematics]], Ψ is used to denote the angle between the tangent and the x-axis in the [[intrinsic coordinates]] system * Again in mathematics, Ψ is also used to denote the [[Digamma function|Digamma]] and [[Polygamma function]]s. * 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 -- for example, see [http://www.iupsys.org/ IUPsyS]. ===psi=== * [[Pounds per square inch]], a unit of pressure {{disambig}}