Definition of "thrash"

thrash

/θɹæʃ/

verb
third-person singular simple present thrashes, present participle thrashing, simple past and past participle thrashed
1. To beat mercilessly.
  Quotations
  But in the town it was well known, when they got home at night, their fat and psychopathic wives would thrash them within inches of their lives.
  1979 November 30, Roger Waters (lyrics and music), “The Happiest Days of Our Lives”, in The Wall‎, performed by Pink Floy
  The rural Midland & Great Northern backwaters from Norfolk to Leicester closed in February 1959 before they could be used there, and thrashing them on the GN main line instead resulted in a memorably poor ride and rattling windows, caused by vibration from their engines and suspect suspension.
  2023 February 22, Howard Johnston, “Southern '313s': is the end now in sight?”, in RAIL, number 977, page 42
2. To defeat utterly.
  Quotations
  Pardew made five changes to the side that thrashed West Ham 5-0 on Wednesday - with players such as James Perch and Alan Smith given the chance to underline their case for a regular starting berth.
  2011 January 8, Paul Fletcher, “Stevenage 3 - 1 Newcastle”, in BBC‎
3. To thresh.
4. To move about wildly or violently; to flail; to labour.
  Quotations
  I rather would be Maevius, thrash for rhymes, / Like his, the scorn and scandal of the times.
  c. 1690, Juvenal, “The Tenth Satire of Juvenal”, in John Dryden, transl., John Dryden: The Major Works, Oxford University Press, published 1987, page 364
  As performers, we girls have our hair. That's the real thing guys want to see. They love to see the long hair move. They want you to thrash it.
  2023, Britney Spears, The Woman in Me‎, Simon and Schuster
5. (software) To extensively test a software system, giving a program various inputs and observing the behavior and outputs that result.
6. (computing) In computer architecture, to cause or undergo poor performance of a virtual memory (or paging) system.
noun
countable and uncountable, plural thrashes
1. (countable) A beat or blow; the sound of beating.
  Quotations
  Even among friends at the dinner-table he talked as though he were denouncing them, or someone else, on a platform; he measured his phrases, built his sentences, cumulated his effects, and pounded his opponents, real or imagined. His humor was glow, like iron at dull heat; his blow was elementary, like the thrash of a whale.
  1918, Henry Adams, The Education of Henry Adams
  As he reeled on wide-braced legs, sobbing for breath, the jungle and the moon swimming bloodily to his sight, the thrash of bat-wings was loud in his ears.
  1934 May, Robert E. Howard, “Queen of the Black Coast”, in Weird Tales
  Spinning full-circle, the aircraft careered out of control. It bounced twice on the waves, each time managing to free itself from the engulfing spray with vigorous thrashes of its one good wing.
  2016, Clark Nida, The Titan Kiss
2. (music, uncountable) Ellipsis of thrash metal.