(grammar) The instrumental case.
A composition written or performed without lyrics, sometimes using a lead instrument to replace vocals.
Essential or central; of great importance or relevance.
He was instrumental in conducting the business.
Pertaining to, made by, or prepared for, an instrument, especially a musical instrument (rather than the human voice).
An instrumental part
(grammar) Applied to a case expressing means or agency, generally indicated in English by by or with with the objective.
the instrumental case