中張牌
also: チュウチャンパイ
Meanings
1
minor tiles; inside tiles
In mahjong, refers to suited tiles numbered 2 through 8, excluding terminals (1 and 9) and honors. Also called 'inside tiles' because they are in the middle of the suit sequence.
from Chinese zhōng zhāng pái
It's difficult to build a hand using only minor tiles.
Minor tiles tend to be safer discards than terminal tiles.