[ slak ]
See synonyms for: slackslackedslackerslacking on

  1. not tight, taut, firm, or tense; a slack rope.

  2. negligent; careless; remiss: slack proofreading.

  1. slow, sluggish, or indolent: He is slack in answering letters.

  2. not active or busy; dull; not brisk: the slack season in an industry.

  3. moving very slowly, as the tide, wind, or water.

  4. Phonetics. weak; lax.

  5. Nautical. easy (def. 15a).

  1. in a slack manner.

  1. a slack condition or part.

  2. the part of a rope, sail, or the like, that hangs loose, without strain upon it.

  1. a decrease in activity, as in business or work: a sudden slack in output.

  2. a period of decreased activity.

  3. Geography. a cessation in a strong flow, as of a current at its turn.

  4. a depression between hills, in a hillside, or in the land surface.

  5. Prosody. (in sprung rhythm) the unaccented syllable or syllables.

  6. British Dialect. a morass; marshy ground; a hollow or dell with soft, wet ground at the bottom.

verb (used with object)
  1. to be remiss in respect to (some matter, duty, right, etc.); leave undone; shirk: He slacked the most important part.

  2. to make or allow to become less active, vigorous, intense, etc.; relax (efforts, labor, speed, etc.); lessen; moderate (often followed by up).

  1. to make loose, or less tense or taut, as a rope; loosen (often followed by off or out).

  2. to slake (lime).

verb (used without object)
  1. to be remiss; shirk one's duty or part.

  2. to become less active, vigorous, rapid, etc. (often followed by up): Business is slacking up.

  1. to become less tense or taut, as a rope; to ease off.

  2. to become slaked, as lime.

Idioms about slack

  1. take up the slack,

    • to pull in or make taut a loose section of a rope, line, wire, etc.: Take up the slack before releasing the kite.

    • to provide or compensate for something that is missing or incomplete: New sources of oil will take up the slack resulting from the embargo.

Origin of slack

First recorded before 900; Middle English adjective slak(e), slakke, Old English slæc, sleac; cognate with Old Norse slakr, Old High German slach, Latin laxus lax

Other words for slack

Other words from slack

  • slack·ing·ly, adverb
  • slackly, adverb
  • slackness, noun
  • un·slacked, adjective
  • un·slack·ing, adjective

Words Nearby slack

Other definitions for slack (2 of 2)

[ slak ]

  1. the fine screenings of coal.

Origin of slack

First recorded in 1200–50; of uncertain origin; compare Middle English sleck “mud, slush, stony soil,” Flemish slecke, Middle Dutch slacke, slecke, Dutch slak, Low German slak(ke), German Schlacke “dross (of metal)” Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use slack in a sentence

British Dictionary definitions for slack (1 of 2)


/ (slæk) /

  1. not tight, tense, or taut

  2. negligent or careless

  1. (esp of water, etc) moving slowly

  2. (of trade, etc) not busy

  3. phonetics another term for lax (def. 4)

  1. in a slack manner

  1. a part of a rope, etc, that is slack: take in the slack

  2. a period of decreased activity

    • a patch of water without current

    • a slackening of a current

  1. prosody (in sprung rhythm) the unstressed syllable or syllables

  1. to neglect (one's duty, etc)

  2. (often foll by off) to loosen; to make slack

  1. chem a less common word for slake (def. 3)

Origin of slack

Old English slæc, sleac; related to Old High German slah, Old Norse slākr bad, Latin laxus lax

Derived forms of slack

  • slackly, adverb
  • slackness, noun

British Dictionary definitions for slack (2 of 2)


/ (slæk) /

  1. small pieces of coal with a high ash content

Origin of slack

C15: probably from Middle Low German slecke; related to Dutch slak, German Schlacke dross

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012