plain-clothes
01
私服の, 平服の
(of a police officer) dressed in civilian clothes while on duty
例
The detectives dressed in plain-clothes to blend in with the crowd during the undercover operation.
覆面捜査中、刑事たちは群衆に溶け込むために私服を着ていた。
The plain-clothes officers quietly monitored the suspect's movements from across the street.
私服の警官は、通りの向こうから静かに容疑者の動きを監視した。
