Meaning of INSTRUMENTAL in English
I. in ‧ stru ‧ men ‧ tal 1 /ˌɪnstrəˈmentl◂, ˌɪnstrʊˈmentl◂/ BrE AmE adjective
1 . be instrumental in (doing) something formal to be important in making something happen:
He was instrumental in developing links with European organizations.
2 . instrumental music is for instruments, not for voices
II. instrumental 2 BrE AmE noun [countable]
a piece of music in which no voices are used, only instruments
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012