General English

  • adjective very tired


  • adjective exhausted. This is not, strictly speaking, a slang word as it derives from ‘knacker’, denoting a worn-out horse or a slaughterer of horses, but has come to be seen as slang because of confusion with knackers, in the sense of testicles. The ultimate origin of the word is probably a dialect word meaning saddle-maker and based on a version of the word knock.