1. (noun)slack dust consisting of a mixture of small coal fragments and coal dust and dirt that sifts out when coal is passed over a sieve Synonyms: quag, slackness, falloff, falling off, slack water, morass, slump, drop-off, quagmire, mire Antonyms: tense, diligent, running(a)
2. (noun)slump, slack, drop-off, falloff, falling off a noticeable deterioration in performance or quality Synonyms: slackness, economic crisis, falloff, slack water, cliff, morass, drop, depression, falling off, quag, lessening, mire, decrease, quagmire, slack, drop-off, slump Antonyms: tense, running(a), diligent
3. (noun)slack, slack water a stretch of water without current or movement Synonyms: quag, slackness, falloff, slack, slack tide, falling off, slack water, morass, slump, drop-off, quagmire, mire Antonyms: diligent, tense, running(a)
4. (noun)mire, quagmire, quag, morass, slack a soft wet area of low-lying land that sinks underfoot Synonyms: quag, slackness, falloff, slop, slack, falling off, slack water, morass, slump, drop-off, quagmire, mire Antonyms: running(a), diligent, tense
6. (adj)slack a cord or rope or cable that is hanging loosely Synonyms: quag, slackness, falloff, falling off, slack water, morass, slump, drop-off, quagmire, mire Antonyms: tense, running(a), diligent
7. (adj)loose, slack not tense or taut Synonyms: idle, promiscuous, informal, easy, wanton, sluttish, escaped, liberal, free, open, lax, loose, unaffixed, on the loose(p), light, slack, at large(p) Antonyms: diligent, tense, running(a)
8. (adj)slack flowing with little speed as e.g. at the turning of the tide Synonyms: loose, lax Antonyms: running(a), tense, diligent
9. (verb)lax, slack lacking in rigor or strictness Synonyms: loose, slack, lax Antonyms: running(a), tense, diligent
10. (verb)slack avoid responsibilities and work, be idle Synonyms: slack off, abate, die away, slake, relax, slow up, slow, slacken, slow down, let up, slack up Antonyms: diligent, tense, running(a)
11. (verb)slack be inattentive to, or neglect Synonyms: slack off, abate, die away, slake, relax, slow up, slow, slacken, slow down, let up, slack up Antonyms: running(a), tense, diligent
12. (verb)slack release tension on Synonyms: slack off, abate, die away, slake, relax, slow up, slow, slacken, slow down, let up, slack up Antonyms: running(a), tense, diligent
13. (verb)slack, slacken, slack up, relax make less active or fast Synonyms: unstrain, decompress, slow down, unbend, slacken, loosen, remit, let up, unlax, slack off, abate, loosen up, slow, loose, slack up, slake, relax, slack, die away, unwind, make relaxed, slow up Antonyms: diligent, tense, running(a)
14. (verb)slow, slow down, slow up, slack, slacken become slow or slower Synonyms: decompress, slow down, unbend, slacken, remit, let up, slack off, abate, loosen up, slow, decelerate, slack up, retard, slake, relax, slack, die away, unwind, slow up Antonyms: running(a), tense, diligent
15. (verb)slake, abate, slack make less active or intense Synonyms: slack off, slack, allay, abate, slow down, slake, slow up, slow, quench, slacken, assuage, relax, die away, let up, slack up Antonyms: tense, running(a), diligent
16. (verb)abate, let up, slack off, slack, die away become less in amount or intensity Synonyms: slack off, slack, ease off, abate, die away, slow up, relax, slacken, slake, slow, slack up, slow down, let up, ease up Antonyms: diligent, tense, running(a)
17. (verb)slack, slake cause to heat and crumble by treatment with water Synonyms: slack off, allay, abate, die away, slake, slack, relax, slow up, assuage, slow, slacken, quench, slow down, let up, slack up Antonyms: tense, running(a), diligent
Synonyms, Thesaurus & Antonyms of 'slack'
English Synonyms and Antonyms
1. slack Slow signifies moving through a relatively short distance, or with a relatively small number of motions in a given time; slow also applies to that which is a relatively long while in beginning or Synonyms: slow, dawdling, dilatory, gradual, lingering, slack, delaying, drowsy, inactive, moderate, sluggish, deliberate, dull, inert, procrastinating, tardy
Synonyms for slack 
