Mahjong term: a winning hand containing two identical chows (same numbers and same suit). Also known as 一盃口 (イーペーコー).
See also: 一盃口 (イーペーコー)
Pure double chow is a hand where you have two identical chows of the same numbers.
Synonymous mahjong term, more commonly used in Japanese mahjong contexts.
Compound of 一色 (one suit) and 二順 (two chows), describing the hand composition.