instrumental

Etymology

From Middle English instrumental, instrumentale, from Medieval Latin īnstrūmentālis.

adj

1. Essential or central; of great importance or relevance.
   He was instrumental in conducting the business.
   Few songwriters have been as instrumental in creating the mold for American music. 2012, Christoper Zara, Tortured Artists: From Picasso and Monroe to Warhol and Winehouse, the Twisted Secrets of the World's Most Creative Minds, part 1, chapter 2, 51
   … Prosser was instrumental in the decision in 2010 to recommence publication of an annual health and safety report, following a period when it had fallen into abeyance. July 29 2020, Ian Prosser discusses with Paul Stephen, “Rail needs robust and strategic plans”, in Rail, page 40
2. Serving as an instrument, medium, means, or agency.
   Maxwell started back to his study, feeling that kind of satisfaction which a man feels when he has been even partly instrumental in finding an unemployed person a remunerative position. 1896, Charles M. Sheldon, chapter 12, in In His Steps
3. (music) Pertaining to, made by, or prepared for an instrument, especially a musical instrument (rather than the human voice).
   instrumental music
   An instrumental part
   Sweet voices mix'd with instrumental sounds. c. 1700, John Dryden, Cymon and Iphigenia
4. (grammar) Applied to a case expressing means or agency, generally indicated in English by by or with with the objective.
   the instrumental case

noun

1. (grammar) The instrumental case.
2. (music) A composition written or performed without lyrics, sometimes using a lead instrument to replace vocals.
   I recommend this album in the face of the fact that five of the eleven songs are the purest filler, dull instrumentals with a harmonica rifling over an indifferent rhythm section. The rest is magnificent […] 1977, Stereo Review, volume 38, page 70