From Middle English slakenen, equivalent to slack +‎ -en.


  • IPA(key): /ˈslæ.kən/
    • (file)
  • Rhymes: -ækən


slacken (third-person singular simple present slackens, present participle slackening, simple past and past participle slackened)

  1. (intransitive) To gradually decrease in intensity or tautness; to become slack.
    The pace slackened.
    • 1908, Kenneth Grahame, The Wind in the Willows:
      He seemed tired, and the Rat let him rest unquestioned, understanding something of what was in his thoughts; knowing, too, the value all animals attach at times to mere silent companionship, when the weary muscles slacken and the mind marks time.
  2. (transitive) To make slack, less taut, or less intense.
    • 1900, Charles W. Chesnutt, The House Behind the Cedars, Chapter I:
      During this interlude, Warwick, though he had slackened his pace measurably, had so nearly closed the gap between himself and them as to hear the old woman say, with the dulcet negro intonation: []
    • 1986, Mari Sandoz, The Horsecatcher:
      Elk slackened the rope so he could walk farther away, and together they went awkwardly up the trail toward the grassy little flat...
  3. To deprive of cohesion by combining chemically with water; to slake.
    to slacken lime

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