noun
bulging shape; tile pattern with a middle-rank extra tile
In mahjong, refers to a specific tile pattern: a complete chow plus an extra tile of the middle rank (e.g., 3-4-4-5). Outside mahjong, it can describe something that bulges in the middle.
この手牌には中ぶくれの形が含まれている。
This hand contains a bulging shape pattern.
中ぶくれの筒は真ん中が膨らんでいる。
A bulging cylinder is swollen in the middle.