gadfly

Etymology

From gad (“(obsolete) sharp point, spike; (dialectal) sharp-pointed rod for driving cattle, horses, etc., goad”) + fly, in the sense of a fly which irritates cattle, etc., by biting them, similar to the prodding of a goad. Gad is derived from Middle English gad, gadde (“metal spike with a sharp point; stick with a sharp point for driving animals, goad; metal bar or rod, ingot; (by extension) lump of material; metal rod for measuring land; (by extension) unit of linear measure equal to about 10 to 16 feet”), borrowed from Old Norse gaddr (“spike; goad”), from Proto-Germanic *gazdaz (“spike; goad”), further etymology uncertain. Sense 2.1.1 (“person who upsets the status quo”) may allude to the Apology by the Greek philosopher Plato (428/427 or 424/423 – 348/347 B.C.E.), where he describes Socrates (c. 470 – 399 B.C.E.) acting as a goad to the Athenian political scene like a gadfly (Ancient Greek μῠ́ωψ (múōps)) arousing a sluggish horse.

noun

1. Any dipterous (“two-winged”) insect or fly of the family Oestridae (commonly known as a botfly) or Tabanidae (horsefly), noted for irritating animals by buzzing about them, and biting them to suck their blood; a gadbee.
   (botfly):
   (horsefly):
   Vengeful Hera transformed her Io] into an animal (a beautiful cow), and imposed upon her the company of a gadfly to sting her continuously, thus forcing her to escape on an endless pilgrimage. 2005, Rafael Argullol, “Introduction”, in Yolanda Gamboa, transl., The End of the World as a Work of Art: A Western Story, Lewisburg, Pa.: Bucknell University Press; Cranbury, N.J.: Associated University Presses, page 48
2. (figurative, also attributively)
   1. A person or thing that irritates or instigates.
      1. (specifically) A person who upsets the status quo by posing novel or upsetting questions, or attempts to stimulate innovation by being an irritant.
         There is a function for the gadfly who poses questions that many specialists would like to overlook. Polemics is healthy. 1977, Morris Kline, Why the Professor Can’t Teach: Mathematics and the Dilemma of University Education, New York, N.Y.: St. Martin’s Press, page 238
         What was required now was the intervention of some men who were not gadflies. […] The logic of [Charles] Pearson's arguments was accepted, up to a point, by a consortium of businessmen. In August 1854, […] the consortium obtained royal assent for […] the Metropolitan Railway. […] In 1859, when it looked as though the Metropolitan Railway Company would be wound up with no line built, he [Pearson] wrote a pamphlet: A Twenty Minutes Letter to the Citizens of London in Favour of the Metropolitan Railway and City Station. Gadfly he may have been, but by this 'letter' he persuaded the Corporation of London to invest £200,000 in the line, a most unusual example of a public body investing in a Victorian railway. 2012, Andrew Martin, “The World of Charles Pearson”, in Underground Overground: A Passenger’s History of the Tube, London: Profile Books, pages 26–27
         Dr. [Carl] Hart, 54, the first tenured African-American science professor at Columbia, is a gadfly among drug researchers and a rock star among advocates for decriminalizing drugs. 10 April 2021, John Leland, “This heroin-using professor wants to change how we think about drugs”, in The New York Times, New York, N.Y.: The New York Times Company, →ISSN, →OCLC, archived from the original on 2022-05-28
   2. Synonym of gadabout (“a person who restlessly moves from place to place, seeking amusement or the companionship of others”)
   3. (derogatory, slang) A person who takes without giving back; a bloodsucker.
      He’s a regular gadfly and takes advantage of his friend’s generosity.