Skip to main content
PlainSpell

slack

/slæk/noun, adjective, adverb, verb

slack is spelled S-L-A-C-K: 5 letters and one syllable. It appears 5.1 times per million words in written English, the 11,015th most frequent word form (wordfreq, 2021 data). As a noun, slack means “The part of anything that hangs loose, having no strain upon it” (English Wiktionary, September 2026). The plural of slack is slacks.

How many letters and syllables are in slack?

Letters5: S-L-A-C-K
Syllables1 (from its American pronunciation)
In writing5.1 times per million words; the 11,015th most frequent word form
Wrong spellings searchednone measured in search

Sources: letters and syllables from the English Wiktionary's hyphenation or pronunciation and the CMU Pronouncing Dictionary; written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).

How common is slack?

Slack appears 5.1 times per million words in written English, the 11,015th most frequent word form in the list.

Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).

How do you pronounce slack?

  • /slæk/

Slack has one syllable (counted from its American pronunciation in the CMU Pronouncing Dictionary).

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: En-au-slack.ogg, Wikimedia Commons (author and licence on each file's page).

Forms of slack

  • slacks plural, present, singular, he/she/it
  • slacker comparative
  • slackest superlative
  • slacking participle, present
  • slacked participle, past

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).

What does slack mean?

The meanings the English Wiktionary records, quoted as written there (source below).

noun

  1. 1

    The part of anything that hangs loose, having no strain upon it.

    the slack of a rope or of a sail

  2. 2

    A dip in a surface.

  3. 3

    In particular, a shallow dell or hollow; a dip in the surface of terrain, such as between hills.

  4. 4

    A low-lying marsh or a pool, especially a tidal or intermittent one which periodically fills and drains.

  5. 5

    Unconditional listening attention given by client to patient.

  6. 6

    Attributive form of slacks (“semi-formal trousers”). (a form of slacks)

  7. 7

    A temporary speed restriction where track maintenance or engineering work is being carried out at a particular place.

  8. 8

    A valley, or small, shallow dell; a sag or saddle in a ridge.

  9. 9

    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.

  10. 10

    Small coal; coal dust.

adjective

  1. 1

    Lax; not tense; not firmly extended.

    a slack rope

  2. 2

    Weak; not holding fast.

    a slack hand

  3. 3

    Moderately warm.

    a slack oven

  4. 4

    Moderate in speed.

    a slack wind

  5. 5

    Lacking diligence or care; not earnest or eager.

    slack in duty or service

  6. 6

    Not active or busy, successful, or violent.

    Business is slack.

  7. 7

    Excess; surplus to requirements.

    the slack capacity of an oil pipeline

  8. 8

    slangVulgar; sexually explicit, especially in dancehall music.

adverb

  1. 1

    Slackly.

    slack dried hops

verb

  1. 1

    To slacken.

  2. 2

    obsoleteTo mitigate; to reduce the strength of.

  3. 3

    To lose cohesion or solidity by a chemical combination with water; to slake.

    Lime slacks.

  4. 4

    To refuse to work as hard as one is supposed to.

    I can't afford to slack. This job is all I have!

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).

Slack in Spanish, French, German and Portuguese

LanguageWords
Spanishflojera, soltura (the part of anything that hangs loose), charco (tidal marsh or periodically filling shallow), carbonilla, carboncillo, cisco (small coal, coal dust)
GermanMarsch (tidal marsh or periodically filling shallow), Schlacke (small coal, coal dust), Senke (small shallow dell or valley), schlaff, lose (not tense), trödelig (not using due diligence or care)
Frenchgravier (small coal, coal dust), lâche (not tense), glander (to procrastinate)
Portugueseenrolar (to procrastinate), frouxo (weak)

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Translations are Wiktionary's, by sense; a linked word has its own PlainSpell page.

Where does slack come from?

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

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).

What to look up after slack