- 1not stretched tight synonym loose She was staring into space, her mouth slack. The rope suddenly went slack. slack muscles
- 2(of business) not having many customers or sales; not busy a slack period Wednesdays are always slack. slack demand for beef
- 3(disapproving) not putting enough care, attention, or energy into something and so not doing it well enough He's been very slack in his work lately. Discipline in the classroom is very slack. We lost because of some slack defending on our part.
adverb Her arms hung slackly by her sides.
noun [uncountable]See slack in the Oxford Advanced Learner's Dictionary
Check pronunciation: slack