If someone or something is instrumental in a process, plan, or system, that person or thing is one of the most important influences in causing it to happen.
She was instrumental in bringing about the prison reform act.监狱改革条例得以出台多亏她大力促成。
(MUSIC)
用乐器演奏的,器乐的
involving only musical instruments, and no singing
instrumental music器乐
an instrumental piece/arrangement器乐曲/器乐编曲
instrumental
noun[ C ]uk/ˌɪn.strəˈmen.təl/us/ˌɪn.strəˈmen.t̬əl/