Etymology: Middle English slak, from Old English sleac; akin to Old High German slah slack, Latin laxus slack, loose, languēre to languish, Greek lagnos lustful and perhaps to Greek lēgein to stop
Date: before 12th century
1. not using due diligence, care, or dispatch ; negligent
a. characterized by slowness, sluggishness, or lack of energy <a slack pace> b. moderate in some quality; especially moderately warm <a slack oven> c. blowing or flowing at low speed <the tide was slack> 3. a. not tight or taut <a slack rope> b. lacking in usual or normal firmness and steadiness ; weak <slack muscles> <slack supervision> 4. wanting in activity ; dull <a slack market> 5. lacking in completeness, finish, or perfection <a very slack piece of work> Synonyms: see negligent • slackly adverb • slackness noun II. verb Date: 13th century intransitive verb 1. to be or become slack 2. to shirk or evade work or duty transitive verb 1. a. to be slack or negligent in performing or doing b. lessen, moderate 2. to release tension on ; loosen 3. a. to cause to abate b. slake 3 III. noun Date: 1756 1. cessation in movement or flow 2. a part of something that hangs loose without strain <take up the slack of a rope> 3. trousers especially for casual wear — usually used in plural 4. a dull season or period 5. a. a part that is available but not used <some slack in the budget> b. a portion (as of labor or resources) that is required but lacking <hired a temp to take up the slack> 6. additional leeway or relief from pressure — usually used with cut <refused to cut me some slack on the schedule> IV. noun Etymology: Middle English slak, from Old Norse slakki Date: 14th century dialect England a pass between hills V. noun Etymology: earlier sleck, probably from Middle Dutch slacke, slecke slag Date: 1729 the finest screenings of coal produced at a mine unusable as fuel unless cleaned
New Collegiate Dictionary. 2001.