noun
standing at attention; standing stiffly upright
Describes a rigid, motionless standing posture, often in military or formal contexts. Can also be used figuratively for someone frozen in place.
新入社員は直立不動で上司の話を聞いていた。
The new employee stood stiffly at attention while listening to the boss.
兵士たちは直立不動の姿勢で命令を待った。
The soldiers waited for orders in a standing-at-attention posture.