psi

¹

[ sahy, psahy ]

noun

, plural psis.

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

psi

²

[ sahy ]

noun

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

psi

³

or p.s.i.

1. pounds per square inch.

psi

¹

/ 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

psi

²

abbreviation for

1. pounds per square inch

Word History and Origins

Origin of psi¹

1350–1400; Middle English < Greek pseî

Origin of psi²

1940–45; shortening of psychic or parapsychic

Example Sentences

They were tested at halftime and found to be inflated to 11 psi, the website reported, instead of the league-mandated minimum of 13.5 psi.

From Washington Times

Such an amount is greater than the bite pressure exerted by some of the strongest jaws in the animal kingdom: Crocodile bites have been measured at up to 3,700 psi.

From Scientific American

The water provides the liquid for the artificial snow itself, and the gravitational energy provides enough water pressure—20 bars, or about 290 psi—to operate the guns, which look like showerheads that spray snow.

From Scientific American

If phi mesons can add to the strong force field, their cousins should, too—and J/psi mesons’ spin polarizations should be similarly impacted by the resulting fluctuations.

From Scientific American

Avoid them by setting your tire pressure low, never more than 5 psi.

From Seattle Times