Psi

;Medical terminology
* Psi-wave pattern
** Psi-wave device
;Astronomical nomenclature
* Psi 2000
** Psi 2000 personnel
* Psi Cancri, a star system
* Psi Epsilon III, a planet
* Psi Octantis, a star system
* Psi Serpentis, a star system
* Psi Epsilon IV, a planet
* Psi Upsilon III, a planet
* Psi Upsilon IV, a planet
;See also
* PSI
fr:Psi