noun
checkmate by a dropped pawn (illegal move)
A shogi rule: delivering checkmate by dropping a pawn is illegal. The term refers to the forbidden move itself.
将棋では打ち歩詰めは反則負けになる。
In shogi, checkmate by a dropped pawn results in an illegal-move loss.
初心者は打ち歩詰めに気をつけなければならない。
Beginners must be careful not to commit an illegal pawn-drop checkmate.
Compound of 打ち (dropping, from 打つ 'to drop a piece'), 歩 (pawn), and 詰め (checkmate). The term is specific to shogi.