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Synonyms

slack

1 American  
[slak] / slæk /

adjective

slacker, comparative slackest superlative
  1. not tight, taut, firm, or tense;

    a slack rope.

    Synonyms:
    relaxed
  2. negligent; careless; remiss.

    slack proofreading.

    Synonyms:
    thoughtless, lazy, lax
  3. slow, sluggish, or indolent.

    He is slack in answering letters.

    Synonyms:
    listless, tardy, dilatory
  4. not active or busy; dull; not brisk.

    the slack season in an industry.

    Synonyms:
    quiet, idle
  5. moving very slowly, as the tide, wind, or water.

  6. Phonetics. weak; lax.

  7. Nautical. easy.


adverb

  1. in a slack manner.

noun

  1. a slack condition or part.

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

  3. a decrease in activity, as in business or work.

    a sudden slack in output.

    Synonyms:
    relaxation
  4. a period of decreased activity.

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

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

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

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

verb (used with object)

slacks, present (3rd person singular) slacked, past participle, past slacking present participle
  1. to be remiss in respect to (some matter, duty, right, etc.); leave undone; shirk.

    He slacked the most important part.

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

    Synonyms:
    slacken, reduce
  3. to make loose, or less tense or taut, as a rope; loosen (often followed by off orout ).

  4. to slake (lime).

verb (used without object)

slacks, present (3rd person singular) slacked, past participle, past slacking present participle
  1. to be remiss; shirk one's duty or part.

    Synonyms:
    malinger
  2. to become less active, vigorous, rapid, etc. (often followed byup ).

    Business is slacking up.

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

  4. to become slaked, as lime.

idioms

  1. take up the slack,

    1. to pull in or make taut a loose section of a rope, line, wire, etc..

      Take up the slack before releasing the kite.

    2. to provide or compensate for something that is missing or incomplete.

      New sources of oil will take up the slack resulting from the embargo.

slack 2 American  
[slak] / slæk /

noun

  1. the fine screenings of coal.


slack 1 British  
/ slæk /

adjective

  1. not tight, tense, or taut

  2. negligent or careless

  3. (esp of water, etc) moving slowly

  4. (of trade, etc) not busy

  5. phonetics another term for lax

"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

adverb

  1. in a slack manner

"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

noun

  1. a part of a rope, etc, that is slack

    take in the slack

  2. a period of decreased activity

    1. a patch of water without current

    2. a slackening of a current

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

"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

verb

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

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

  3. chem a less common word for slake

"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
slack 2 British  
/ slæk /

noun

  1. small pieces of coal with a high ash content

"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

Other Word Forms

Derived Forms

Inflected Forms

Adjectives

Participles

Conjugated Forms

Present

Past

Future

Etymology

Origin of slack1

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

Origin of slack2

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)”

Explanation

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!"

Keep Reading on Vocabulary.com

Vocabulary lists containing slack

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

Bank of Canada Gov. Tiff Macklem has noted inflation is currently being held back by continued slack in Canada’s economy, which is growing again after having contracted for two consecutive quarters.

From The Wall Street Journal Jul. 20, 2026

He needs to repay the slack that allowed him a full Indian Premier League stint.

From BBC Jun. 24, 2026

Still, Wall Street seems to be willing to cut Warsh some slack as he tries to sort through things.

From Barron's Jun. 18, 2026

After college he did not slack off, noted his biographer Christopher Simon Sykes.

From Los Angeles Times Jun. 12, 2026

The rigging went slack, tar melted and dripped, the wind died to fitful breezes.

From "Carry On, Mr. Bowditch" by Jean Lee Latham

“You’re a slacker. You remind me of your father when he went here. He was a slacker, too.”

From Los Angeles Times Mar. 30, 2026

Our unnamed protagonist, a slacker with a goatee, is no protester.

From Los Angeles Times Feb. 4, 2026

That realisation manifests in the lovestruck slacker rock of Dragonfly, and the finger-plucked Neptune Baby, with its refrain, "I'm a boat, and you are the water".

From BBC Apr. 27, 2025

Some of the plot is just unnecessary padding, like Daniel’s girlfriend troubles and slacker mentality, spiking in an odd scene where he hysterically bemoans his own uselessness.

From New York Times Jun. 20, 2024

He believed that if he didn't return to Germany, he would be considered "unpatriotic" and a "slacker."

From Nazi Saboteurs by Samantha Seiple

The UK has the slackest regulation of all EU members; other member states are much more stringent in their approach.

From The Guardian May 24, 2013

It was the most abstract and highly changeable concert I’ve seen this group perform, and also the slackest: inspired on one level, frustrating on another.

From New York Times Feb. 10, 2011

Drew was allowed to indulge in that slackest kind of writing, the day-by-day journal.

From Time Magazine Archive

In the weeks before Christmas, when retail sales are usually at their highest, retailers were cutting prices as though it were slackest of seasons.

From Time Magazine Archive

How they discussed and made fun over the humours of the bazaar; nor was Gerald's wit the slackest, nor his mirth the most lagging. 

From The Long Vacation by Yonge, Charlotte Mary

He stopped by the birthday party wearing his work uniform: a white, button-down shirt and black slacks.

From Los Angeles Times Jul. 17, 2026

A styling group stores troves of neutral tone crew and V-neck sweaters, button-down shirts, slacks and extra pairs of the Silver Lining Opticians “Carbon” glasses at an off-site building, current and former employees said.

From The Wall Street Journal May 31, 2026

It was a blur of champagne, full sized In-N-Out cheeseburgers, chic ushers wearing Dior uniforms with snug grey sweaters and slacks that pooled perfectly at the leg.

From Los Angeles Times May 15, 2026

Eugene Levert, chain-smoking next to a stack of books while wearing a vertical blue-striped button-down and khaki slacks, looked the scholarly mirror of Doug Lamplugh, in a horizontal blue-striped polo and khaki shorts.

From Slate May 4, 2026

All were instructed to dress in conservative casual wear: the women in blouses, straight skirts, and flat shoes; the men in polo shirts or button-downs, slacks, and loafers.

From "Blink" by Malcolm Gladwell

If teammates slacked off in practice after partying late, he’d shoot them extra hard puck passes.

From Seattle Times Feb. 2, 2024

Speaking to the press, he said: "I've given my heart and soul. I can't think there'll be too many cricket fans out there who would think I've slacked off for a moment."

From BBC Aug. 1, 2023

It's not as if Eigenberg ever slacked off in maintaining his physique; he also plays a main role in "Chicago Fire."

From Salon Jul. 23, 2023

"We were just active on defense. When they had their runs, we slacked off," Brooks said.

From Fox News Nov. 19, 2021

In the visitor’s locker room, Gaines, his face slacked with sweat and his hair matted, closed the door to parents and fans and drew the players around him.

From "Friday Night Lights: A Town, A Team, And A Dream" by H.G. Bissinger

I’ve heard it repeatedly from experts: The greatest risk of working out alone is bad form, leading to inefficient movement, slacking off and higher chance of injury.

From The Wall Street Journal Jan. 4, 2026

With her apartment a flood zone and her landlord slacking off on the maintenance, Linda and her daughter are forced to live at a nearby hotel.

From Salon Oct. 9, 2025

Florida’s experience isn’t an endorsement of slacking at the start of the year, something the Washington Capitals learned from their playoff streak ending.

From Washington Times Oct. 1, 2023

“When are you going to stop slacking off?”

From Seattle Times Sep. 30, 2023

But he was slacking off and took no personal interest in me.

From "Hole in My Life" by Jack Gantos

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