The form trouser is used as a modifier. trouser 用作修饰词。
1 N-PLURAL [oft a pair of NOUN] 裤子 Trousers are a piece of clothing that you wear over your body from the waist downwards, and that cover each leg separately.
裤子 [mainly British] in AM, usually use 美国英语通常用 pants
2 to
wear the trousers→see: wear View usage for:All yearsLast 10 yearsLast 50 yearsLast 100 yearsLast 300 years