plainclothes
adj. 便衣的（尤指不穿制服的警察）
例句
He was arrested by plainclothes detectives as he walked through the customs hall.
他穿过海关大厅时被便衣侦探逮捕了。
《柯林斯英汉双解大词典》
Riot police and plainclothes security men have ringed universities.
防暴警察和便衣包围了众大学。
Even clergymen visiting the area had to be accompanied by plainclothes policemen.
甚至牧师到这里来都要便衣警察的陪同。
