Dictionary.com

psi

1
[ sahy, psahy ]
/ saɪ, psaɪ /
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noun, plural psis.

the 23rd letter of the Greek alphabet (Ψ, ψ).
the group of consonant sounds represented by this letter.

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Origin of psi

1
1350–1400; Middle English <Greek pseî

Definition for psi (2 of 3)

psi2
[ sahy ]
/ saɪ /

noun

any purportedly psychic phenomenon, as psychokinesis, telepathy, clairvoyance, or the like.

Origin of psi

2
1940–45; shortening of psychic or parapsychic

Definition for psi (3 of 3)

psi

or p.s.i.


pounds per square inch.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

British Dictionary definitions for psi (1 of 2)

psi1

abbreviation for

pounds per square inch

British Dictionary definitions for psi (2 of 2)

psi2
/ (psaɪ) /

noun

the 23rd letter of the Greek alphabet (Ψ, ψ), a composite consonant, transliterated as ps
  1. paranormal or psychic phenomena collectively
  2. (as modifier)psi powers
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for psi (1 of 2)

psi
[ sī, psī ]

n.

The 23rd letter of the Greek alphabet.

Medical definitions for psi (2 of 2)

ψ

The Greek letter psi. Entries beginning with this character are alphabetized under psi.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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