Dictionary.com
Thesaurus.com
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:

Jeremy Jacquet: Made a goal-saving challenge to deny Igor Jesus an early goal and was impressive but still had a few moments where he was slack and lacked discipline.

From BBC Aug. 29, 2026

His assistant coaches, mostly a group of his former Granada Hills players, have to pick up the slack sometimes with the subsequent practices early in the following week.

From Los Angeles Times Aug. 20, 2026

However, with labor market slack only gradually increasing, focus now turns to Wednesday’s U.S. inflation data, Deutsche Bank analysts say in a note.

From The Wall Street Journal Aug. 10, 2026

Indeed, he suggests, the Fed can respond to demand shocks with rate cuts “as long as slack is increasing and inflation pressures from wages are easing.”

From MarketWatch Aug. 10, 2026

The princess’s eyes drifted shut and her face went slack.

From "The Long-Lost Home" by Maryrose Wood

In another writer’s hands, the soft-handed seat-fillers of his slacker masterpiece “Office Space” would be contemptible.

From Salon Sep. 6, 2026

The prototypical Gen Xer is resilient and cynical, a “latchkey kid” turned disaffected slacker, raised on MTV and limited parental supervision.

From The Wall Street Journal Jul. 31, 2026

It should be noted that Paul Cummins is no slacker himself.

From Los Angeles Times Mar. 21, 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

That night Dr. Marrigan told me that I was too smart to be a slacker faculty kid.

From "Wintergirls" by Laurie Halse Anderson

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 any year it would have been a tasteful, artful job of the soft sell, but in this, television's slackest season, the Eastern Airlines commercial looked like a masterwork.

From Time Magazine Archive

"I was going to say that my practice could get along very well for a day or two, since it is the slackest time in the year."

From The Memoirs of Sherlock Holmes by Sir Arthur Conan Doyle

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

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

She added with a laugh that she’d brainstormed speech material the previous night while shaving her legs, despite the fact that she was outfitted in slacks at the ceremony.

From Los Angeles Times Mar. 15, 2026

The dads were in their after-work best: slacks and a sweater, some sort of brown shoe.

From The Wall Street Journal Jan. 14, 2026

I change into black slacks and a dressy blouse.

From "Split the Sky" by Marie Arnold

As time elapsed, Sand’s rate of production never slacked.

From The Wall Street Journal Aug. 7, 2026

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

“I don’t think I did very good job here of doing what I need to do become the best pitcher I could be. I definitely slacked off and just didn’t put the work in.”

From Seattle Times Feb. 13, 2020

Martha made sure that none of us slacked off for even a single day.

From "Courage to Soar" by Simone Biles

If nothing is on the books, it could look like you’re slacking off.

From The Wall Street Journal Aug. 20, 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

Almost across the board, inflation showed few signs of slacking.

From Los Angeles Times Oct. 13, 2022

Some folks can look at you and tell if you’re even thinking about slacking off, they’ll add some work to you faster than you can say Jack Robinson.

From "Bud, Not Buddy" by Christopher Paul Curtis

Vocabulary.com logo
by dictionary.com

Join 12,000,000 vocabulary learners

Start learning new words today on VocabTrainer.
You'll remember them forever.

Start training