psi

¹ American  

Or p.s.i.

1. pounds per square inch.

---

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.

---

psi ³ American  

[sahy] / saɪ /

noun

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

---

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 psi²

1350–1400; Middle English < Greek pseî

Origin of psi³

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 • Dec. 21, 2023

And one computer modeling study has estimated that a relatively large great white shark could sink its teeth into prey with a force of almost 4,000 psi.

From Scientific American • Jun. 21, 2023

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

From Seattle Times • Dec. 9, 2022

If pressure after the reducing valve is low, which generally means below 40 psi, Ray installs a new valve, and that often solves the problem.

From Washington Post • Apr. 25, 2022

The letter psi, in Greek, is shaped like a tulip.

From "The Secret History" by Donna Tartt