psi

¹ American  

[sahy, psahy] / saɪ, psaɪ /

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 American  

[sahy] / saɪ /

noun

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

---

psi ³ American  

Or p.s.i.

1. pounds per square inch.

---

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

---

psi ² British  

abbreviation

1. pounds per square inch

---

Etymology

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

To test the new hypothesis, the Brookhaven scientists plan to re-create their experiment with a different meson, called the J/psi meson, which is made of a quark-antiquark pair of a different favor.

From Scientific American

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

From Seattle Times