INSTRUMENT'AL, adjective Conducive as an instrument or means to some end; contributing aid; serving to promote or effect an object; helpful. The press has been instrumental in enlarging the bounds of knowledge. 1. Pertaining to instruments; made by instruments; as instrumental music, distinguished form vocal music, which is made by the human voice.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI