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Phi (letter): Wikis


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Phi uc lc.svg
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
Obsolete letters
Digamma uc lc.svg Digamma Qoppa uc lc.svg Qoppa
San uc lc.svg San Sampi uc lc.svg Sampi
Other characters
Stigma uc lc.svg Stigma Sho uc lc.svg Sho
Heta uc lc.svg Heta

Greek diacritics

Phi (uppercase Φ, lowercase φ or math symbol ϕ), pronounced [ˈfi] in modern Greek and /ˈfaɪ/ or sometimes /ˈfiː/ in English,[1] is the 21st letter of the Greek alphabet. In modern Greek, it represents [f], a voiceless labiodental fricative. In Ancient Greek it represented [pʰ], an aspirated voiceless bilabial plosive (from which English ultimately inherits the spelling "ph" in words derived from Greek). In the system of Greek numerals it has a value of 500 (φʹ) or 500,000 (͵φ). The Cyrillic letter Ef (Ф, ф) arose from Φ.


Use as a symbol

The lower-case letter \varphi \, (or often its variant, \phi \,) is often used to represent the following:

The upper-case letter Φ is used as a symbol for:

The diameter symbol in engineering, , is often incorrectly referred to as "phi". This symbol is used to indicate the diameter of a circular section, for example "⌀14", means the diameter of the circle is 14 units.


In Unicode, there are multiple forms of the phi letter:

Character Name Correct appearance Your browser Usage
U+03A6 GREEK CAPITAL LETTER PHI \Phi\,\! Φ used in Greek texts
U+03C6 GREEK SMALL LETTER PHI \varphi\,\! or \phi\,\! φ used in Greek texts
U+03D5 GREEK PHI SYMBOL \phi\,\! ϕ used in mathematical and technical contexts[2]
U+0278 LATIN SMALL LETTER PHI \phi\,\! ɸ used in IPA to symbolise a voiceless bilabial fricative

In some older fonts that are not yet compatible with Unicode 3.0 from 1998, the U+03D5 GREEK PHI SYMBOL might be represented by the "loopy" \varphi symbol instead.[2] This is no longer a correct representation. The U+03C6 GREEK SMALL LETTER PHI may be presented as either the "stroked" \phi\,\! glyph, but preferably as the "loopy" \varphi glyph.[2]

In HTML/XHTML, the upper and lower case phi character entity references are Φ (Φ) and φ (φ) respectively.

In LaTeX, the math symbols are \Phi (\Phi\,\!), \phi (\phi\,\!), and \varphi (\varphi\,\!).

See also


  1. ^ [faɪ]: Collins English Dictionary, 3rd ed. (1991); New Oxford American Dictionary, 2nd ed. (2005) (transcribed "[fʌɪ] "). [fiː] is used increasingly in the media, especially when representing the golden ratio: see, for example, The Da Vinci Code and the Criminal Minds episode, "Masterpiece".
  2. ^ a b c "Representative Glyphs for Greek Phi" (PDF). UTR #25: Unicode support for mathematics. 

Simple English

Common letters
ΑaA ΜmEm
ΒbBe ΝnEn
GgGe ΟοO
ΔdDe ΠpPe
hHa ЖжZhe
ΕɛE RrAr
ΖzZe SsEs
ΗeEe ΤtTe
ΘөEth UuU
ΙiI FfEf
JjJe WwWa
ΚkKa ΧxXa
LlEl ОWоwWe
Uncommon letters
Digamma Qoppa
San Sampi
Other letters
Stigma Sho

Greek alphabet

Phi (uppercase/lowercase Φ φ), is the letter of the Greek alphabet, used to represent the "ph" sound in Ancient Greek. This sound changed to "f" some time in the 1st century AD, and in Modern Greek the letter denotes the "f" sound. In the system of Greek numerals, it has a value of 500. The Cyrillic letter Ф came from Phi. In English, φ is pronounced like "f" but transliterated (re-written) as "ph" in words which originate in Ancient Greek. In those words which originate in Modern Greek, such as feta cheese, φ is translitterated as "f". the letter Phi is used in the golden Ratios and Phi represents the number aproximately: 1.618033988749.


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