Definition of "instrumental"

The head is not more native to the heart, The hand more instrumental to the mouth

c. 1599–1602 (date written), William Shakespeare, “The Tragedie of Hamlet, Prince of Denmarke”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act I, scene ii]

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.

2020 July 29, Ian Prosser discusses with Paul Stephen, “Rail needs robust and strategic plans”, in Rail, page 40

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

He defended the use of instrumental music in public worship.

1849–1861, Thomas Babington Macaulay, The History of England from the Accession of James the Second, volumes (please specify |volume=I to V), London: Longman, Brown, Green, and Longmans

Sweet voices mix'd with instrumental sounds.

c. 1700, John Dryden, Cymon and Iphigenia

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