[in.stru.men.tal] adj (14c) 1 a: serving as a means, agent, or tool "was ~ in organizing the strike" b: of, relating to, or done with an instrument or tool
2: relating to, composed for, or performed on a musical instrument
3: of, relating to, or being a grammatical case or form expressing means or agency
4: of or relating to instrumentalism
5: operant 3 "~ learning" "~ conditioning" -- instrumental n -- in.stru.men.tal.ly adv