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From Wikipedia, the free encyclopedia

Rho 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

Rho (uppercase Ρ, lowercase ρ or ϱ), pronounced /ˈroʊ/ in English, is the 17th letter of the Greek alphabet. In the system of Greek numerals it has a value of 100. It is derived from Semitic Rêš "head" (see Resh). Its uppercase form is not to be confused with the Roman letter P, however both are typeset using the same glyph.

The letter Rho has religious significance within Christianity. When fused within a single typespace with the Greek letter Chi, it forms the labarum, which is used to represent Jesus Christ.

Rho is generally classed as a liquid (together with lambda and sometimes the nasals mu and nu), which has important implications for morphology. It is pronounced similarly to the letter r in languages with a Latin-derived alphabet. In polytonic orthography a rho at the beginning of a word is conventionally written with a rough breathing (equivalent to h) — — and a double rho within a word is written with a smooth breathing over the first rho and a rough breathing over the second — ῤῥ — apparently reflecting an aspirated or voiceless pronunciation in Ancient Greek, hence the various Greek-derived English words which start with rh or contain rrh. The name of the letter is written in Greek as ῥῶ (polytonic) or ρω/ρο (monotonic).

Letters that arose from rho include Roman R and Cyrillic Er (Р).

Former Rhode Scholars are entitled to use the Greek letter rho as a designation of their status. When used, the symbol should precede the name. [1]


Common notational uses

The characters Ρ, ρ and ϱ are also used outside its Greek alphabetical context in science and mathematics.

  • In economics to represent the discount rate of future pence cash flows
  • In molecular biology to represent the Rho protein responsible for termination of RNA synthesis. In such occasions, it is often represented as ϱ ("rho symbol" U+03F1), to avoid confusion with the Latin letter p
  • In ecology to represent the population damping ratio where ρ = λ1 / |λ2|.


In Unicode, the upper and lower case are encoded at U+03A1 and U+03C1 respectively.

See also


  1. ^ "Oxford University Calendar: Notes on Style". Oxford University Gazette. 2009-03-26. Retrieved 2009-06-02. 


Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

The Universal Character Set
Greek uc rho.png
Greek and Coptic U+03A1




Ρ (lowercase, uppercase)

  1. The lower case letter rho (ρο), the 17th letter of the modern Greek alphabet.



  1. The number 100 in Greek numerals.

  1. The number 100,000 in Greek numerals.

See also

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