What is "psi"

23rd letter of the Greek alphabet. Use for "psychic force, paranormal phenomenon" dates from 1942 (probably from psychic (adj.)).

Etymology 1 n. 1 (context countable English) The twenty-third letter of Classical Greek and Modern Greek and the twenty-fifth letter of Old Greek and Ancient Greek. 2 (context uncountable parapsychology English) A form of psychic energy. Etymology 2

alt. pound per square inch (qualifier: an imperial unit of pressure) init. pound per square inch (qualifier: an imperial unit of pressure)

1. n. a unit of pressure [syn: pounds per square inch]

2. the 23rd letter of the Greek alphabet

Psi or PSI or Ψ may refer to:

Psi (uppercase , lowercase ; Psi) is the 23rd letter of the Greek alphabet and has a numeric value of 700. In both Classical and Modern Greek, the letter indicates the combination /ps/ (as in English word "lapse").

For Greek loanwords in Latin and modern languages with Latin alphabets, psi is usually transliterated as "ps". In English, the letter is pronounced or sometimes . (In Greek, it is pronounced .)

The letter's origin is uncertain. It may or may not derive from the Phoenician alphabet. It appears in the 7th century BC, expressing /ps/ in the Eastern alphabets, but /kʰ/ in the Western alphabets (the sound expressed by Χ in the Eastern alphabets). In writing, the early letter appears in an angular shape . There were early graphical variants that omitted the stem ("chickenfoot-shaped psi" as: or ).

The Western letter (expressing /kʰ/, later /x/) was adopted into the Old Italic alphabets, and its shape is also continued into the Algiz rune of the Elder Futhark. The classical Greek letter was adopted into the early Cyrillic alphabet as " Ѱ".

PSI is an album by the industrial rock band Pitchshifter, released in 2002 (see 2002 in music). Their previous two albums had been released on a major label, but this was released by the minor Mayan Records, a subsidiary label owned by Sanctuary Records. "Eight Days" and "Shutdown" were released as singles.

Psi is a free instant messaging client for the XMPP protocol (including such services as Google Talk) which uses the Qt toolkit. It runs on Linux (and other Unix-like operating systems), Windows, Mac OS X and eComStationPsi build for OS/2. Version 0.15, ZIP package. ( OS/2).

Ready-to-install deb and RPM packages are available for many Linux distributions. Successful ports of Psi were reported for Haiku, FreeBSD and Sun Solaris operating systems.

Due to Psi's free/open-source nature, several forks have appeared, which occasionally contain features that may appear in future official Psi versions. These official and unofficial builds are documented on their external wiki page.

PSI is an ab initio computational chemistry package originally written by the research group of Henry F. Schaefer, III ( University of Georgia). It performs high-accuracy quantum computations on small to medium-sized molecules.

PSI4 is the latest release of the program package - it is open source, released as free under the GPL through GitHub. Primary development of PSI4 is currently conducted by Daniel Crawford ( Virginia Tech), David Sherrill ( Georgia Tech), Justin Turney ( University of Georgia), and Rollin King ( Bethel University). PSI4 is available on Linux releases such as Fedora and Ubuntu.

Psi is a DC character created by Paul Kupperberg and Carmine Infantino for Daring New Adventures of Supergirl #1 (November 1982).

Psi (Ѱ, ѱ) is a letter in the early Cyrillic alphabet, derived from the Greek letter psi (Ψ, ψ). It represents the sound /ps/, as in English naps. According to the school rules developed in the sixteenth and seventeenth centuries, such as Meletius Smotrytsky's grammar book, it was intended for use in words loaned from Greek—but it was occasionally used for writing native words, for example Ukrainian (psy, “dogs”). It was used especially in words relating to the Church, as can be seen in its continuing use in Church Slavonic.

Psi was eliminated from the Russian orthography along with ksi, omega, and yus in the Civil Script of 1708 ( Peter the Great's Grazhdansky Shrift), and has also been dropped from other secular languages. It continues to be used in Church Slavonic.