ψ

See also: ѱ, Ψ, 𐌙, Ѱ, 屮, ⋔, and ₼

ψ U+03C8, ψ GREEK SMALL LETTER PSI ← χ [U+03C7] Greek and Coptic ω → [U+03C9]

Character variations

𝜓 U+1D713, 𝜓 MATHEMATICAL ITALIC SMALL PSI ← 𝜒 [U+1D712] Mathematical Alphanumeric Symbols 𝜔 → [U+1D714]

Translingual

Symbol

ψ

Doke's obsolete symbol for a voiced retroflex click, [ɡ͜𝼊]

1. Psychology.
2. Psychiatry.
3. Parapsychology, psychics.
4. (quantum mechanics) A wavefunction.
5. (electrical engineering) Electric flux.
6. (physics, biochemistry) Water potential in cells.
7. (astrology, dated) Neptune.
8. (astrology, italic) asteroid (16) Psyche (a stylized 𝜓)
9. (Christianity) The Psalms (a book in the Bible).
10. (phonetics, dated) a voiceless retroflex click, IPA ⟨k͜𝼊⟩.

    (turned) a voiced retroflex click, IPA ⟨ɡ͜𝼊⟩.

11. (UPA) A bilabial trill, IPA ⟨ʙ⟩.

Usage notes

(quantum physics): Some texts use Ψ (uppercase) for the actual wavefunction that appears in the time-dependent Schrödinger equation, and ψ (=Ψe^iEt/ħ) (lowercase) for the time-independent spatial wave function that may exist for stationary states (and which then appears in the time-independent Schrödinger equation), but this distinction is not always observed. Otherwise, the distinction may be made by providing the arguments.

Ancient Greek

Etymology

Derived from its majuscule counterpart Ψ.

Letter

ψ • (ps) (lowercase, uppercase Ψ)

1. Lower-case psi (ψεῖ), the 23rd letter of the ancient Greek alphabet. It represented the consonant cluster /ps/ in the Eastern Greek alphabet and the voiceless aspirated velar plosive /kʰ/ in the Western Greek alphabet (compare Etruscan 𐌙 khe). It is preceded by χ and followed by ω.

Derived terms

See also psi

• ψ΄, ͵ψ
• ѱ, Ѱ (Cyrillic)
• ⲯ, Ⲯ (Coptic)

See also

• (Greek-script letters) Α α, Β β, Γ γ, Δ δ, Ε ε, Ζ ζ, Η η, Θ θ, Ι ι, Κ κ, Λ λ, Μ μ, Ν ν, Ξ ξ, Ο ο, Π π, Ρ ρ, Σ σ ς, Τ τ, Υ υ, Φ φ, Χ χ, Ψ ψ, Ω ω
• (non-Classical letters) Ϝ ϝ, Ͷ ͷ, Ͱ ͱ, Ϻ ϻ, Ϙ ϙ, Ͳ ͳ
• (punctuation) · ;
• (diacritics) ᾿ ῾ ◌́ ◌̀ ῀ ¨

Greek

Letter

ψ • (ps) (lowercase, uppercase Ψ)

1. The lower case letter psi (ψι), the 23rd letter of the modern Greek alphabet.

Derived terms

• ψ΄ (“700”)
• ͵ψ (“700,000”)

See also

• Appendix:Greek alphabet
• (Greek-script letters) Α α, Β β, Γ γ, Δ δ, Ε ε, Ζ ζ, Η η, Θ θ, Ι ι, Κ κ, Λ λ, Μ μ, Ν ν, Ξ ξ, Ο ο, Π π, Ρ ρ, Σ σ ς, Τ τ, Υ υ, Φ φ, Χ χ, Ψ ψ, Ω ω
• (non-Classical letters) Ϝ ϝ, Ͷ ͷ, Ͱ ͱ, Ϻ ϻ, Ϙ ϙ, Ͳ ͳ
• (punctuation) · ;
• (diacritics) ᾿ ῾ ◌́ ◌̀ ῀ ¨