(slak) adjective
1. Hanging or extended loosely.
2. Loose or careless in performance; remiss; tardy; slovenly; slow; also, weak; loose: a slack mouth.
3. Lacking activity; not brisk or pressing: a slack season.
4. Listless; limp: a slack grip.
5. Flowing sluggishly, as water between the ebb and flow of the tide; also, blowing slowly, as a wind.
6. Incomplete; underdone; unfinished. See synonyms under SLOW.
—v.t.
1. To slacken.
2. To slake, as lime.
—v.i.
3. To be or become slack.
—noun
1. The part of anything, as a rope, that is slack or loose; also, a slack condition; looseness.
2. A period of inactivity; a slack season.
3. An extent of water where there is no current.
4. plural Loose–fitting trousers worn by both men and women as part of a casual sports costume; also, cotton or wool trousers in a military uniform.
—adverb In a slack manner; slackly. [OE slœc]
—slack′ly adverb
—slack′·ness noun

(slak) noun
Small coal; screenings. [Cf. LG slacke]

(slak) noun Scot. & Brit. Dial.
1. A dry hollow or gully.
2. A bog.
3. A common.
4. A natural slope of ground. [<ON slakki dip, depression]