psi

[ 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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“Was” is used for the indicative past tense of “to be,” and “were” is only used for the subjunctive past tense.

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Origin of psi

1350–1400; Middle English <Greek pseî

Words nearby psi

pseudovector, pseudoxanthoma elasticum, psf, PSG, pshaw, psi, psia, psid, psig, psilanthropism, psilocin

Other definitions for psi (2 of 3)

psi²

[ sahy ]

/ saɪ /

noun

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

Compare pseudoscience, parapsychology.

Origin of psi

1940–45; shortening of psychic or parapsychic

Other definitions 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. 2022

How to use psi in a sentence

Just above 45 psi, I flipped the pump chuck off and spun the wheel on its axle, bracing for the aerosolized mist of sealant that might come from a gap in the bead seat.
This New Valve Could Make Tubeless Tires Not Suck|agintzler|January 26, 2022|Outside Online
Lighthouse outside of PSI, in Dev Tools or packaged by NPM as an open Node project, can be calibrated to simulate various scenarios.
Google changes Core Web Vitals metrics; How to use lab and field data for optimization|Detlef Johnson|June 8, 2021|Search Engine Land
They tend to have a PSI in the 2,000 to 3,000 range—sometimes more—and are ideal for more intense tasks like cleaning large decks and patios, the side of the house, boats, and utility vehicles.
The best pressure washer for cleaning away mud, oil, paint and more|Jeremy Helligar|March 18, 2021|Popular-Science
Medium size jobs require a PSI between 2,000 and 2,800, with a 2 to 3 GPM.
The best pressure washer for cleaning away mud, oil, paint and more|Jeremy Helligar|March 18, 2021|Popular-Science

There are two sets of steps leading from the front doors of Phi Kappa Psi house.
I Was Gang Raped at a UVA Frat 30 Years Ago, and No One Did Anything|Liz Seccuro|December 16, 2014|DAILY BEAST
The bonds of Phi Kappa Psi brotherhood were too strong to break.
I Was Gang Raped at a UVA Frat 30 Years Ago, and No One Did Anything|Liz Seccuro|December 16, 2014|DAILY BEAST
The Charlottesville Police did indeed have jurisdiction over the Phi Kappa Psi house.
I Was Gang Raped at a UVA Frat 30 Years Ago, and No One Did Anything|Liz Seccuro|December 16, 2014|DAILY BEAST
I have not sued Phi Kappa Psi, the University of Virginia, or any of the individuals involved.
I Was Gang Raped at a UVA Frat 30 Years Ago, and No One Did Anything|Liz Seccuro|December 16, 2014|DAILY BEAST
Will PSI (private sector involvement) become common in future bailouts?
What Bailout? Six Reasons to Love Cyprus|Kevin Fallon|March 18, 2013|DAILY BEAST
Certainly it had protected him on Antar, and with equal certainty it must have been responsible for the psi powers he possessed.
Insidekick|Jesse Franklin Bone
We know the Auerbach cylinder will store a psi impulse, but we don't know how.
Sense from Thought Divide|Mark Irvin Clifton
I didn't need any psi talent for that, it was an inevitable part of his pattern.
Sense from Thought Divide|Mark Irvin Clifton
What we really lacked in psi was the ability to orient its phenomena.
Sense from Thought Divide|Mark Irvin Clifton
I could say psi was a flow of positrons, and it would mean as much.
Sense from Thought Divide|Mark Irvin Clifton

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

paranormal or psychic phenomena collectively
(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)

The Greek letter psi. Entries beginning with this character are alphabetized under psi.

Medical definitions for psi (2 of 2)

psi

[ sī, psī ]

The 23rd letter of the Greek alphabet.