Word.ws English Dictionary

slack

/slæk/

slack noun: the part of anything that hangs loose, having no strain upon it. Also the attributive form of slacks.

Noun (1)

slack (countable and uncountable, plural slacks)

  1. (uncountable) The part of anything that hangs loose, having no strain upon it.
    • the slack of a rope or of a sail
    • take in the slack
  2. A dip in a surface.
    • Richardson states that a low joint, a short distance from Haslam's Creek Bridge, was, in his opinion, the cause of the accident. […] [He] told Morgan, the Permanent Way Inspector, that there was a "slack" in the road on the Parramatta side of Haslam's Creek Bridge, […] I can positively state […]...1858, New South Wales. Parliament. Legislative Council, Votes & Proceedings, page 1020
    • […] a road may be kept up to approximately the same level at all times, and a fair surface maintained by rolling in large patches occasionally, as well as opening slacks in the road when they appear and effecting petty repairs. […] a series of slacks will begin to show in the run of the wheels; or...1904, Public Works and Journal of Civil Engineering, page 90
  3. In particular, a shallow dell or hollow; a dip in the surface of terrain, such as between hills.
    • Cauldstane Slap, or rather Slack, is a much frequented pass, through which the periodical droves of black cattle are transported into England.1815, Alexander Pennecuik, The Works of Alexander Pennecuik ...: Containing the Description of Tweeddale, and Miscellaneous Poems, page 141
    • ... for they had at that time observed the side of the brae, where the little green slack was situated, covered with a sheet of flame for a moment.1837, James Hogg, The hunt of Eildon. The adventures of Basil Lee. Adam Bell. Duncan Campbell. An old soldier's tale. Katie Cheyne. The long pack. A country funeral. The shepherd's calendar, page 249
  4. (countable) A low-lying marsh or a pool, especially a tidal or intermittent one which periodically fills and drains.
    • The "slacks" I have mentioned are fresh-water pools which extend just inside the outer sandhills. Being mostly dry in summer, the shore fowl love to breed there. Peewits nest on their banks, and the long grasses and sand willow[…]1901, The Pall Mall Magazine, page 138
    • ... in that quarter lay the great slack of the Watch Hill, the yellow slack that feeds the Blackburn, and in which horse and rider might readily disappear for ever.1983 [1897], Ernest Hamilton, The Outlaws of the Marches
    Synonyms:
    slough
  5. (uncountable, psychotherapy) Unconditional listening attention given by client to patient.
    • The counselor is directed to give his client "free attention," or "slack," performing a kind of vigil, a version of Carl Rogers's "unconditional positive regard."1979, Richard Dean Rosen, Psychobabble, page 93
    • We have apparently been doing this all our lives, since we were first distressed. This collection of ancient habits seems to be "energized" by the presence, or even the promise, of "slack" or free attention from any person in the situation […]1983, Harvey Jackins, The Reclaiming of Power, page 14

Adjective

slack (comparative slacker, superlative slackest)

  1. Lax; not tense; not firmly extended.
    • a slack rope
  2. Weak; not holding fast.
    • a slack hand
  3. Moderately warm.
    • a slack oven
  4. Moderate in speed.
    • a slack wind
  5. Lacking diligence or care; not earnest or eager.
    • slack in duty or service
    • The Lord is not ſlacke cõcerning his promiſe (as ſome men count ſlackneſſe)[…].1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC, 2 Peter 3:9, column 2
  6. Not active or busy, successful, or violent.
    • Business is slack.
    • the slack period following the main tourist season
    Synonyms:
    slow, moderate, easy
  7. Excess; surplus to requirements.
    • the slack capacity of an oil pipeline
  8. (Caribbean, Jamaica, slang) Vulgar; sexually explicit, especially in dancehall music.
  9. Lax.

Adverb

slack (not comparable)

  1. Slackly.
    • slack dried hops
    • Her clothes hung slack on her.

Verb

slack (third-person singular simple present slacks, present participle slacking, simple past and past participle slacked)

  1. (ambitransitive) To slacken.
    • I maruell I heare no nevves of Dromio, either hee ſlackes the matter, or betrayes his maiſter, I dare not motion anie thing to Stellio, till I knovve vvhat my boy hath don; Ile hunt him out, if the loiterſacke be gone ſpringing into a tauerne, Ile fetch him reeling out.c. 1590 (date written), [John Lyly], Mother Bombie. […], London: […] Thomas Scarlet for Cuthbert Burby, published 1594, →OCLC, Act II, scene ii, signature C3, verso
    • In this business of growing rich, poor men […] should slack their pace.1692–1717, Robert South, Twelve Sermons Preached upon Several Occasions, volume (please specify |volume=I to VI), London
  2. (obsolete) To mitigate; to reduce the strength of.
    • Ne did ſhe let dull ſleepe once to relent, / Nor wearineſſe to ſlack her haſt, but fled / Euer alike,[…].1590, Edmund Spenser, “Book III, Canto VII”, in The Faerie Queene. […], London: […] [John Wolfe] for William Ponsonbie, →OCLC, stanza 2, page 494
  3. To lose cohesion or solidity by a chemical combination with water; to slake.
    • Lime slacks.
  4. To refuse to work as hard as one is supposed to.
    • I can't afford to slack. This job is all I have!

Noun (2)

slack (plural slacks)

  1. A temporary speed restriction where track maintenance or engineering work is being carried out at a particular place.
    • This pitfall, beginning in February and finishing in May, resulted in a drop of about 3 ft. in the platform level; during this period it was necessary to level the track three times weekly, and impose a service slack of 15 m.p.h. The subsidence appears now to have finished, and normal speed is once...1939 June, “Pertinent Paragraphs: Pitfalls”, in Railway Magazine, page 456
    • The train runs slowly with frequent slacks for bridge and culvert repairs. At one point occurs the changeover from left- to right-hand running.1949 September and October, “The "Nord Express"”, in Railway Magazine, page 336

Noun (3)

slack (plural slacks)

  1. (countable) A valley, or small, shallow dell; a sag or saddle in a ridge.
    • Red Ringan sped, and the spearmen led, Up Goranberry Slack; Aye, many a wight, unmatched in fight, Who never more came back. And bloody set the westering sun, And bloody rose he up; […]1812, Walter Scott, Minstrelsy of the Scottish Border: Consisting of Historical and Romantic Ballads Collected in the Southern Counties of Scotland, with a Few of Modern Date Founded Upon Local...
    • "I see some folk coming through the slack yonder, […]"1871, Walter Scott, Waverly Novels, page 159
  2. A flat-bottomed, hollow zone within a sand-dune system that has developed over impervious strata, sometimes due to erosion or blow-out of the dune system; its flat base level is therefore close to or at the permanent water-table level, and therefore has rich, marshy flora, with Salix species (willows) as typical woody colonisers.

Noun (4)

slack (uncountable)

  1. Small coal; coal dust.
    • One of the important improvements of recent years has been attained by mixing the peat pulp as it passes through the grinding machine, with other inflammable materials, such as bituminous coal dust, or slack […]1905, Colliery Engineer, volume 25, page 107
    • It had rather a woolly and uneven beat and was inclined to prime, but there was no trouble with steaming even though the tender contained mostly small slack and dust.1959 April, P. Ransome-Wallis, “The Southern in Trouble on the Kent Coast”, in Trains Illustrated, London: Ian Allan Publishing, →ISSN, →OCLC, page 220
    Synonyms:
    culm

Proper noun capitalized: Slack

Slack (countable and uncountable, plural Slacks)

  1. A surname.
  2. A hamlet in Ashover parish, North East Derbyshire district, Derbyshire (OS grid ref SK3362).
  3. A hamlet in Heptonstall parish, Metropolitan Borough of Calderdale, West Yorkshire (OS grid ref SD9828).
  4. A hamlet in the Metropolitan Borough of Kirklees, near Outlane, West Yorkshire (OS grid ref SE0817).
  5. (Internet) A real-time collaboration app and platform launched in 2013.
    • On Slack, the employees of Strategic Programming chattered about metadata tagging issues.2025, Liz Pelly, Mood Machine: The Rise of Spotify and the Costs of the Perfect Playlist, 1st edition, New York: Atria Books, →ISBN

Also used as

slack is also the attributive form of slacks.

slack meaning in Hindi, Bengali and Tagalog

slack in Hindi

सुस्त

slack in Bengali

স্ল্যাক

slack in Tagalog

loose part of anything
lundo

Examples of slack in a sentence

  • On all lines of course there are slacks, but not slacks of a serious nature; and that there was any such slack or depression in the rails as spoken of by Richardson I positively deny.1858, New South Wales. Parliament. Legislative Council, Votes & Proceedings, page 1020:
  • […] to make good the voids under the sleeper […] to take out "slacks" in the rail level […]1951, Institution of Civil Engineers (Great Britain), Proceedings of the Joint Engineering Conference, 1951, page 45:
  • Then she became a gay grey mare, / And stood in yonder slack; And he became a gilt saddle, / And sat upon her back.1845, Alexander Whitelaw, The Book of Scottish Ballads Collected and Illustrated with Historical and Critical Notices, London : Blackie...
  • The great interest of the sandhills is the slacks.1880, Littell's Living Age, page 448:

All 40 example sentences with slack

Synonyms of slack

All synonyms of slack

Forms of slack

Noun
pluralslacks
Adjective
comparativeslacker
superlativeslackest
Verb
third-person singular presentslacks
present participleslacking
past participleslacked
pastslacked
Proper noun
pluralSlacks

Plural of slack: slacks

Origin of slack

From Middle English slak, from Old English slæc (“slack”), from Proto-Germanic *slakaz. For sense of coal dust, compare slag.

From Middle English slakken, slaken, from Old English slacian, from Proto-Germanic *slakōną (“to slack, slacken”).

Either from the adjective in Etymology 1 or the verb in Etymology 2.

Words formed from slack

Phrases with slack

6 more phrasesFewer phrases

Words that rhyme with slack

48 more rhymesFewer rhymes

Questions about slack

What does slack mean?
Slack means the part of anything that hangs loose, having no strain upon it.
What is slack in Hindi?
Slack in Hindi is सुस्त. See Slack meaning in Hindi.
How do you use slack in a sentence?
On all lines of course there are slacks, but not slacks of a serious nature; and that there was any such slack or depression in the rails as spoken of by Richardson I positively deny.
What part of speech is slack?
Slack can be a noun, an adjective, an adverb or a verb.
How do you pronounce slack?
Slack is pronounced /slæk/.
What is the plural of slack?
The plural of slack is slacks.

Words near slack in the dictionary

  1. slabstones
  2. slabwise
  3. Slaby
  4. Slabys
  5. SLAC
  6. slack
  7. slack Alice
  8. slack Alices
  9. slack ass
  10. slack bob
  11. slack bobs

Source and license

Adapted from Wiktionary: slack (page history and authors); Slack (page history and authors); slack (Hindi, IndicTrans2 machine translation) (model and license); slack (Bengali, IndicTrans2 machine translation) (model and license). Text available under the Creative Commons Attribution-ShareAlike 4.0 license. Word.ws reformatted the entry and added links. Wiktionary data of 2026-09-02.

Last updated:

Pronunciation audio from Wikimedia Commons, each file under its own free license: En-au-slack.ogg.

Cite this entry: “slack.” Word.ws, https://word.ws/slack. Based on Wiktionary, CC BY-SA 4.0.