slack

¹ American  

[slak] / slæk /

adjective

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.

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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)

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)

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.

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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

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adverb

1. in a slack manner

noun

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

   take in the slack

2. a period of decreased activity

3. 1. a patch of water without current

   2. a slackening of a current

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

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

slack ² British  

/ slæk /

noun

1. small pieces of coal with a high ash content

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Other Word Forms

• slackingly adverb
• slackly adverb
• slackness noun
• unslacked adjective
• unslacking adjective

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!"

Example Sentences

“During big snowstorms, firms often let employees work from home for the week, and similarly they cut them some slack when gas prices hit $4, or in California $5 or even $6.”

From MarketWatch • Apr. 1, 2026

They require friction, in a world that grows increasingly slack and unrequiring of its inhabitants.

From Slate • Mar. 20, 2026

“Meaningful pass-through from higher global energy prices to core CPI is unlikely given excess slack in the Canadian economy, but that is an upside risk the longer the war drags on,” Davenport said.

From The Wall Street Journal • Mar. 16, 2026

Christian Anderson, guard, Texas Tech: After the Red Raiders lost Toppin, Anderson helped pick up the scoring slack.

From Los Angeles Times • Mar. 16, 2026

I follow the line out with my other hand and try pulling on it, maybe get enough slack to slip it off, but the line slips through my fingers and I can’t get a grip.

From "The Young Man and the Sea" by Rodman Philbrick

Related Words

• lackadaisical
• lax
• lethargic
• permissive
• sluggish
• stagnant