psi

¹ American  

Or p.s.i.

1. pounds per square inch.

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psi ² American  

[sahy, psahy] / saɪ, psaɪ /

noun

psis plural

1. the 23rd letter of the Greek alphabet (Ψ, ψ).

2. the group of consonant sounds represented by this letter.

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psi ³ American  

[sahy] / saɪ /

noun

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

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psi ¹ British  

/ psaɪ /

noun

1. the 23rd letter of the Greek alphabet (Ψ, ψ), a composite consonant, transliterated as ps

2. 1. paranormal or psychic phenomena collectively

   2. ( as modifier )

      psi powers

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psi ² British  

abbreviation

1. pounds per square inch

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Etymology

Origin of psi²

1350–1400; Middle English < Greek pseî

Origin of psi³

1940–45; shortening of psychic or parapsychic

Example Sentences

Leonard’s work showed the exact opposite of Exponent’s conclusions: The drop in the Patriots’ footballs’ p.s.i was consistent with the Ideal Gas Law; the smaller drop in pressure in the Colts’ balls was not.

From New York Times • Jan. 22, 2016