adjective
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).
(music) A pause in the vocals of a song, usually occurring midway through, in which a musical instrument replaces the vocals.
(grammar) Applied to a case expressing means or agency, generally corresponding to the English use of prepositions such as by, with, through, or by means of with the objective case.
noun
(grammar) The instrumental case.
(music) A composition written or performed without lyrics or singing, using a lead instrument to replace vocals.