(grammar) The instrumental case.

(music) A composition written or performed without lyrics, sometimes using a lead instrument to replace vocals.

Essential or central; of great importance or relevance.

Serving as an instrument, medium, means, or agency.

(music) Pertaining to, made by, or prepared for an instrument, especially a musical instrument (rather than the human voice).

(grammar) Applied to a case expressing means or agency, generally indicated in English by by or with with the objective.