If you slow down at the end of a race, you slack off. When you use slack this way, it means to reduce your speed, to be sluggish, or to be negligent.

If something is loose, it's also said to be slack. A clothesline, for example, is slack if it is just hanging loosely between two trees. If you pull the clothesline tight, you reduce the slack. The root word of slack is the Old English word slæc, which means "loose or careless." When you scold your friend for being careless about his responsibilities, you can say, "Pick up the slack!"

Definitions of slack
  1. adjective
    not tense or taut
    slack and wrinkled skin”
    slack sails”
    “a slack rope”
    synonyms: loose
    lacking in strength or firmness or resilience
  2. noun
    the quality of being loose (not taut)
    synonyms: slackness
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    type of:
    looseness, play
    movement or space for movement
  3. noun
    a cord or rope or cable that is hanging loosely
    “he took up the slack
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    type of:
    a line made of twisted fibers or threads
  4. verb
    release tension on
    slack the rope”
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    type of:
    loose, loosen
    make loose or looser
  5. verb
    make less active or fast
    synonyms: relax, slack up, slacken
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    type of:
    decrease, lessen, minify
    make smaller
  6. verb
    make less active or intense
    synonyms: abate, slake
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    type of:
    decrease, lessen, minify
    make smaller
  7. verb
    become less in amount or intensity
    synonyms: abate, die away, let up, slack off
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    type of:
    decrease, diminish, fall, lessen
    decrease in size, extent, or range
  8. verb
    become slow or slower
    synonyms: slacken, slow, slow down, slow up
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    type of:
    become weaker
  9. adjective
    lacking in rigor or strictness
    slack in maintaining discipline”
    synonyms: lax
    characterized by neglect and undue lack of concern
  10. noun
    a noticeable deterioration in performance or quality
    “a gradual slack in output”
    synonyms: drop-off, falling off, falloff, slump
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    type of:
    declension, decline in quality, deterioration, worsening
    process of changing to an inferior state
  11. verb
    avoid responsibilities and work, be idle
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    type of:
    fiddle, goldbrick, shirk, shrink from
    avoid (one's assigned duties)
  12. verb
    be inattentive to, or neglect
    “He slacks his attention”
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    type of:
    fail to attend to
  13. noun
    a stretch of water without current or movement
    “suddenly they were in a slack and the water was motionless”
    synonyms: slack water
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    type of:
    a large and unbroken expanse or distance
  14. adjective
    flowing with little speed as e.g. at the turning of the tide
    slack water”
    (of fluids) not moving or flowing
  15. noun
    a soft wet area of low-lying land that sinks underfoot
    synonyms: mire, morass, quag, quagmire
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    type of:
    bog, peat bog
    wet spongy ground of decomposing vegetation; has poorer drainage than a swamp; soil is unfit for cultivation but can be cut and dried and used for fuel
  16. noun
    dust consisting of a mixture of small coal fragments and coal dust and dirt that sifts out when coal is passed over a sieve
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    type of:
    debris, detritus, dust, junk, rubble
    the remains of something that has been destroyed or broken up
  17. verb
    cause to heat and crumble by treatment with water
    slack lime”
    synonyms: slake
    see moresee less
    alter by exposure to air with conversion at least in part to a carbonate
    type of:
    cause to be hydrated; add water or moisture to
Word Family

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