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psi 1

 (sī, psī, psē)
The 23rd letter of the Greek alphabet. See Table at alphabet.

[Middle English, from Late Greek, from Greek psei.]

psi 2

Parapsychological phenomena or abilities considered as a group.

[Shortening and alteration of parapsychological.]

psi 3

pounds per square inch
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


abbreviation for
(Units) pounds per square inch


1. (Letters of the Alphabet (Foreign)) the 23rd letter of the Greek alphabet (Ψ, ψ), a composite consonant, transliterated as ps
2. (Psychology)
a. paranormal or psychic phenomena collectively
b. (as modifier): psi powers.
3. (Alternative Belief Systems)
a. paranormal or psychic phenomena collectively
b. (as modifier): psi powers.
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(saɪ, psaɪ)

n., pl. psis.
the 23rd letter of the Greek alphabet (Ψ, ψ).
[1350–1400; Middle English < Greek pseî]



of or pertaining to parapsychological manifestations or abilities.
[1940–45; shortening of psychic or parapsychic]


or p.s.i.,

pounds per square inch.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.


Pounds per square inch: a unit for measuring pressure. One PSI equals the pressure resulting from a force of one pound force acting over an area of one square inch. See pound.
Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.psi - a unit of pressure
pressure unit - a unit measuring force per unit area
2.psi - the 23rd letter of the Greek alphabet
Greek alphabet - the alphabet used by ancient Greeks
alphabetic character, letter of the alphabet, letter - the conventional characters of the alphabet used to represent speech; "his grandmother taught him his letters"
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.


1 ABBR =pounds per square inchkg/cm²


2 [saɪ] NPL (= psychic phenomena) → fenómenos mpl paranormales
Collins Spanish Dictionary - Complete and Unabridged 8th Edition 2005 © William Collins Sons & Co. Ltd. 1971, 1988 © HarperCollins Publishers 1992, 1993, 1996, 1997, 2000, 2003, 2005


n no pl
(= letter)Psi nt
(= psychic phenomena)Psi nt
Collins German Dictionary – Complete and Unabridged 7th Edition 2005. © William Collins Sons & Co. Ltd. 1980 © HarperCollins Publishers 1991, 1997, 1999, 2004, 2005, 2007
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In addition, because the harm-based weights were developed based on the potential harm associated with each PSI (e.g., mortality and readmission) at the patient level, we hypothesized that the harm-based PSI-90 would have a stronger correlation with hospital mortality and readmission rates than the volume-based PSI-90.
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Lessaris noted that the new high-horsepower engine display is the result of PSI's subsidiary, Power Great Lakes, recently being appointed a "4000 Series Gas Center of Excellence" by Perkins Engines.