Rho (letter)

Rho (Ρ ρ) is the 17th letter of the Greek alphabet. In the system of Greek numerals is has a numeric value of 100.

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.

The lower-case letter ρ is used as a symbol for several things:

• In mathematics, the radius in a polar coordinate system.
• In physics, the density of a material.