instrumental
B2Adjektiv/US /ˌɪnstrəmˈɛntəl/ ĭnstr-əm-ĔNT-əl; UK /ˌɪnstrəmˈɛntəl/ ĭnstr-əm-ĔNT-əl/
Acting as an instrument; serving as a means; contributing to promote; conductive; helpful; serviceable; as, he was instrumental in conducting the business.
