psiPronunciation: (sī, psī), [key]
the 23rd letter of the Greek alphabet (Ψ, ψ).
the group of consonant sounds represented by this letter.
psiPronunciation: (sī), [key]
any purportedly psychic phenomenon, as psychokinesis, telepathy, clairvoyance, or the like. Cf. pseudoscience, parapsychology.
pounds per square inch. Also,p.s.i.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.