Rho (letter)

Greek alphabet
Α α Alpha	Β β Beta
Γ γ Gamma	Δ δ Delta
Ε ε Epsilon	Ζ ζ Zeta
Η η Eta	Θ θ Theta
Ι ι Iota	Κ κ Kappa
Λ λ Lambda	Μ μ Mu
Ν ν Nu	Ξ ξ Xi
Ο ο Omicron	Π π Pi
Ρ ρ Rho	Σ σ Sigma
Τ τ Tau	Υ υ Upsilon
Φ φ Phi	Χ χ Chi
Ψ ψ Psi	Ω ω Omega
obsolete letters
Ϝ ϝ Digamma	Ϻ ϻ San
Ϙ ϙ Qoppa	Ϡ ϡ Sampi

Rho (upper case Ρ, lower case ρ) 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 ר)

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, 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 ρώ (monotonic).

Rho is used to designate a list of items in the APL programming language.

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

Lower case ρ is used in physics to represent density and resistivity, and in economics to represent the discount rate of future cash flows.

Rho (letter)

See also