a.

1. 可作为手段的；有帮助的[F][（+in/to）]
   Her help was instrumental in tracking down the criminal.

   她的协助对追捕到罪犯起了相当作用。

2. （使用）器械的；（使用）仪器的
   instrumental navigation

   仪表导航

3. 用乐器演奏的；为器乐谱写的
   He composed both vocal and instrumental music.

   他既谱写声乐曲也谱写器乐曲。

4. 【哲】工具主义的
5. 【语】工具格的

n.[C]

1. 器乐曲
2. 【语】工具格；工具字（或词组）

adj.

1. serving as a means of pursuing an aim.
2. (of music) performed on instruments, with no vocals.
3. relating to an implement or measuring device.
4. Grammar  denoting or relating to a case of nouns and pronouns indicating a means or instrument.

n.