foul; illegal play; illegal move
Used in sports contexts for an action that breaks the rules, such as a foul, misplay, or illegal move.
If you commit a foul in soccer, the opposing team is awarded a free kick.
審判はその反則プレーを見逃さなかった。
The referee did not overlook that illegal play.
Compound of 反則 (violation of rules) and プレー (play, from English).