Merriam-Webster Logo
SINCE 1828
Menu
×

An Encyclopædia Britannica Company

1

slack

adjective \ ˈslak \
See What's Trending Now See More Trending Words

Definition of slack

1 : not using due diligence, care, or dispatch : negligent
2 a : characterized by slowness, sluggishness, or lack of energy
  • a slack pace
b : moderate in some quality; especially : moderately warm
  • a slack oven
c : blowing or flowing at low speed
  • the tide was slack
3 a : not tight or taut
  • a slack rope
b : lacking in usual or normal firmness and steadiness : weak
  • slack muscles
  • slack supervision
4 : wanting in activity : dull
  • a slack market
5 : lacking in completeness, finish, or perfection
  • a very slack piece of work
—

slackly

adverb
—

slackness

noun

See slack defined for English-language learners

See slack defined for kids

Examples of slack in a Sentence

  1. His broken arm hung slack at his side.

  2. The rope suddenly went slack.

  3. He accused the government of slack supervision of nuclear technology.

Origin and Etymology of slack

Middle English slak, from Old English sleac; akin to Old High German slah slack, Latin laxus slack, loose, languēre to languish, Greek lagnos lustful and perhaps to Greek lēgein to stop

slack Synonyms

Synonyms

careless, derelict, disregardful, lax, lazy, neglectful, neglecting, negligent, remiss;

Antonyms

attentive, careful, conscientious, nonnegligent;

Near Antonyms

meticulous, painstaking, punctilious;

cautious, chary, circumspect, gingerly, guarded;

alert, heedful, heeding, mindful, observant, regardful, regarding, vigilant, wary, watchful;

foresighted, forethoughtful, provident, responsible;

thinking, thoughtful;

concerned, interested;

Related Words

heedless, incautious, irresponsible, reckless, wild;

unguarded, unwary;

forgetful;

disregardful, disregarding, inattentive, oblivious, thoughtless, unheeding, unmindful, unthinking;

apathetic, indifferent, unconcerned, uninterested;

Synonym Discussion of slack

negligent, neglectful, lax, slack, remiss mean culpably careless or indicative of such carelessness. negligent implies inattention to one's duty or business.
    • negligent about writing a note of thanks
neglectful adds a more disapproving implication of laziness or deliberate inattention.
    • a society callously neglectful of the poor
lax implies a blameworthy lack of strictness, severity, or precision.
    • a reporter lax about accurate quotation
slack implies want of due or necessary diligence or care.
    • slack workmanship
remiss implies blameworthy carelessness shown in slackness, forgetfulness, or neglect.
    • had been remiss in their familial duties
2

slack

verb

Definition of slack

intransitive verb
1 : to be or become slack
2 : to shirk or evade work or duty
transitive verb
1 a : to be slack or negligent in performing or doing
b : lessen, moderate
2 : to release tension on : loosen
3 a : to cause to abate
b : slake 3

See slack defined for English-language learners

Examples of slack in a Sentence

  1. They need to stop slacking and get down to work.

  2. the skipper ordered the crew to slack off the sheets on the mainsail

First Known Use of slack

13th century

slack Synonyms

Synonyms

ease, loosen, relax, slacken;

Antonyms

strain, stretch, tense, tension, tighten;

Near Antonyms

attach, bind, fasten, tie;

constrain, restrain;

Related Words

detach, free, unbind, undo, unfasten, untie;

3

slack

noun

Definition of slack

1 : cessation in movement or flow
2 : a part of something that hangs loose without strain
  • take up the slack of a rope
3 : trousers especially for casual wear —usually used in plural
4 : a dull season or period
5 a : a part that is available but not used
  • some slack in the budget
b : a portion (as of labor or resources) that is required but lacking
  • hired a temp to take up the slack
6 : additional leeway or relief from pressure —usually used with cut
  • refused to cut me some slack on the schedule

First Known Use of slack

1756

4

slack

noun

Definition of slack

dialectal, England
: a pass between hills

Origin and Etymology of slack

Middle English slak, from Old Norse slakki

5

slack

noun

Definition of slack

: the finest screenings of coal produced at a mine unusable as fuel unless cleaned

Origin and Etymology of slack

earlier sleck, probably from Middle Dutch slacke, slecke slag

Phrases Related to SLACK

Related Phrases

SLACK Defined for English Language Learners

slack

adjective

Definition of slack for English Language Learners

  • : not stretched or held in a tight position

  • : not busy : lacking the expected or desired activity

  • : doing something poorly because you are not putting enough care or effort into it

slack

verb

Definition of slack for English Language Learners

  • : to give little or no effort or attention to work

SLACK Defined for Kids

1

slack

adjective \ ˈslak \

Definition of slack for Students

1 : careless 1, negligent
  • They were slack in all things, without order or discipline.
  • —Jack London, The Call of the Wild
2 : not energetic : slow
  • a slack pace
3 : not tight or firm
  • a slack rope
  • a slack jaw
4 : not busy or active
  • Business is slack.
2

slack

verb

Definition of slack for Students

slacked; slacking
1 : to make or become looser, slower, or less energetic
2 : to avoid work
—

slacker

\ˈsla-kər\ noun
3

slack

noun

Definition of slack for Students

1 : a part (as of a rope or sail) that hangs loose without strain
2 slacks plural : dressy pants
3 : a portion (as of work or resources) that is required but lacking
  • He was hired to take up the slack.
4 : additional relief from pressure
Hint: This sense is usually used with cut.
  • Can you cut me some slack on the schedule?

Learn More about slack

  1. See words that rhyme with slack Thesaurus: All synonyms and antonyms for slack Spanish Central: Translation of slack Nglish: Translation of slack for Spanish speakers Britannica English: Translation of slack for Arabic speakers

Seen and Heard

What made you want to look up slack? Please tell us where you read or heard it (including the quote, if possible).

show hide

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

WORD OF THE DAY

bloviate

play

to speak or write verbosely and windily

Get Word of the Day daily email!

TRENDING NOW

  1. lowlife 'a person of low moral character'

  2. kakistocracy 'government by the worst people'

  3. slimeball 'a morally repulsive or odious person'

  4. salacious 'arousing or appealing to sexual desire'

  5. oligarch 'government in which a small group exercises control'

SEE ALL

BROWSE DICTIONARY

slack

Test Your Vocabulary

Odd Habits and Quirks Quiz

  • image1926873504
  • Which of the following best describes an easily irritated person?
True or False

Test your knowledge - and maybe learn something along the way.

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Words at Play

alt-5ad8fc71357ed
Words We're Watching: 'Bluebeard,' the Verb

No, it's not a coiffure trend

alt-5ad8d3361fb97
Where 'Cliff-hangers' Come From

You're on the edge of your seat

alt-5ad77fad37d22
What the #@*% Is a ‘Grawlix'?

We can thank Beetle Bailey.

alt-5ad76a1542e73
'Altho' vs. 'Although'

Altho doesn't get much love.

Ask the Editors

image1760257654
2017 Word of the Year: Behind the Scenes

How we chose 'feminism'

video-title-words-of-the-year-1066
Words of the Year: 1066

Or, Why Pig Meat is Called 'Pork' and Cow Meat is Called 'Beef'

video-literally
Literally

How to use a word that (literally) drives some people nuts.

video-his-or-her
Is Singular 'They' a Better Choice?

The awkward case of 'his or her'

Word Games

image1926873504
Odd Habits and Quirks Quiz

Test your knowledge of strange human behaviors.

Take the quiz
cats-on-impossible-timber
More Confusing Words—Quiz

How many of these commonly confused words do you know?

Take the quiz
True or False
True or False?

Test your knowledge - and maybe learn something along the way.

Take the quiz
SCRABBLE® Sprint
SCRABBLE® Sprint

SCRABBLE® fans, sharpen your skills!

Play the game
Tip: Synonym Guide
Examples: slack in a Sentence