Psi (letter)

For other uses, see Psi.

Psi (uppercase/lowercase Ψ ψ) is the 23rd letter of the Greek alphabet. It is used to represent the "ps" sound in Ancient and Modern Greek. In the system of Greek numerals, it has a value of 700. Letters that came from it include Cyrillic Ѱ.

Greek alphabet
Αα	Alpha	Νν	Nu
Ββ	Beta	Ξξ	Xi
Γγ	Gamma	Οο	Omicron
Δδ	Delta	Ππ	Pi
Εε	Epsilon	Ρρ	Rho
Ζζ	Zeta	Σσς	Sigma
Ηη	Eta	Ττ	Tau
Θθ	Theta	Υυ	Upsilon
Ιι	Iota	Φφ	Phi
Κκ	Kappa	Χχ	Chi
Λλ	Lambda	Ψψ	Psi
Μμ	Mu	Ωω	Omega
Other letters
Ϝϝ	Digamma	Ⱶⱶ	Heta
Ϻϻ	San	Ϙϙ	Koppa
Ϡϡ	Sampi	Ϛϛ	Stigma
Ϸϸ	Sho
Category Commons

In mathematics, the uppercase [math]\displaystyle{ \Psi }[/math] is used as a variable for sets of sentences (in logic), and the lowercase [math]\displaystyle{ \psi }[/math] is used to represent the sum of reciprocals of Fibonacci numbers. Other applications include the polygamma function, the gamma function and the super golden ratio.

Psi (letter) Media

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  The Greek alphabet on a black-figure pottery vessel, with an archaic chickenfoot-shaped psi.

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  One epigraphic letter shape of ancient Greek letter Psi.

Related pages

• Phi