from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. The 23rd letter of the Greek alphabet. See Table at alphabet.
  • n. Parapsychological phenomena or abilities considered as a group.
  • abbr. pounds per square inch

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The twenty-third letter of Classical and Modern Greek and the twenty-fourth letter of Old and Ancient Greek.
  • n. A form of psychic energy.
  • Pounds per square inch (an imperial unit of pressure)

from The Century Dictionary and Cyclopedia

  • n. A Greek letter, Ψ, ψ. It belongs to the Ionic alphabet, and stands for ps or phs. The character may be a modification of Φ, φ.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. the 23rd letter of the Greek alphabet
  • n. a unit of pressure


from The American Heritage® Dictionary of the English Language, 4th Edition

Middle English, from Late Greek, from Greek psei.
Shortening and alteration of parapsychological.

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Ancient Greek ψῖ, the name for the twenty-third letter of the alphabet (Ψ, ψ).

from Wiktionary, Creative Commons Attribution/Share-Alike License



  • In spinor form the wave-field is psi = (psi_A, psi_ {A’}).

    Dark Matter: Still Dark.

  • The term psi was coined as a neutral term for psychic phenomena in 1942 by British psychologist Robert Thouless.


  • Virtually all meditative traditions take for granted that what we call psi is simply the initial stages of awareness of deeper levels of reality.


  • Entangled Minds and Conscious Universe, Radin gives lectures and presentations around the world on his studies in what he calls psi (psychic) phenomena. stories

  • They need to be though: even the most ardent believers in "psi" (the Greek letter is used as a blanket term to cover psychic phenomena) accept that evidence in favour of it is made up of small anomalies that are often difficult to identify with any certainty.

    Boing Boing: August 28, 2005 - September 3, 2005 Archives

  • With such a little tank (20oz.), 3000 – 4000 psi is required to inflate so many tires, namely 40 road tires from empty to 120 psi with a single tank.

    Technical FAQ with Lennard Zinn: Blowing up tires, taking them off, and more

  • Or posts that equated belief in psi phenomena with superstition, and I replied with citations to replicated scientific studies showing that psi phenomena are real.

    A Childish Question About Immigration, Bryan Caplan | EconLog | Library of Economics and Liberty

  • We are motivated by psychological intentions and organic needs, so psi, which is mediated through conscious and unconscious psychological drives, strongly reflects those needs.


  • Some people today still use occult terms like “astral body” when referring to psi, but most scientifically minded researchers regard occult lore only as metaphors.


  • And telepathy or perception goes out of kilter first because the psi is a very delicate factor.

    Highways in Hiding


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