'Gamma' (uppercase 'Γ', lowercase 'γ') is the third letter of the
Greek alphabet. In the system of
Greek numerals it has a value of 3. It was derived from the
Phoenician letter Gimel 
Gimel
. Letters that arose from Gamma include the Roman
C and
G and the Cyrillic letters
Ge Г and
Ghe Ґ.
In
Modern Greek, it represents either a
voiced velar fricative or a
voiced palatal fricative . In
Ancient Greek, it represented a
voiced velar stop . Before velars, it represents a
velar nasal in Modern as well as Ancient Greek, and a double gamma represents a
prenasalized voiced velar stop ().
Use as a symbol or a term
Main articles: Gamma (disambiguation)
Gamma is often used to denote a variable in
mathematics and
physics.
In certain areas it has a specific meaning, such as representing
gamma radiation, such as gamma waves.