slack

Etymology 1

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

noun

1. (uncountable) The part of anything that hangs loose, having no strain upon it.
   the slack of a rope or of a sail
   take in the slack
2. (countable) A tidal marsh or shallow that periodically fills and drains.
3. (uncountable, psychotherapy) Unconditional listening attention given by client to patient.
   The counselor is directed to give his client "free attention," or "slack," performing a kind of vigil, a version of Carl Rogers's "unconditional positive regard." 1979, Richard Dean Rosen, Psychobabble, page 93
   We have apparently been doing this all our lives, since we were first distressed. This collection of ancient habits seems to be "energized" by the presence, or even the promise, of "slack" or free attention from any person in the situation […] 1983, Harvey Jackins, The Reclaiming of Power, page 14
4. Attributive form of slacks (“semi-formal trousers”).
   The breeches formerly worn with those spiral leggings have been succeeded by full length, slack-type trousers which are loose at the knee and around the calf. 1943, Jacob Armstrong Swisher, Iowa in Times of War, State Historical Society of Iowa, page 124
   Recently though, slack manufacturers have been cuddling under the wings of the clothing industry to a greater extent than ever, for it has become good business to promote separate slacks and sport coats as a coordinated sales unit. 1970, Harry A. Cobrin, The Men’s Clothing Industry: Colonial Through Modern Times, New York, N.Y.: Fairchild Publications, Inc., page 7
   At that time, it was customary for male college students in Peking to wear long gowns. With a pair of slacks and leather shoes, plus a scarf in the winter, Shu looked very handsome. I tried to wear the gown for two days, and gave it up because I found it difficult to reach the slack pockets under it. 2004, Pei Pin Han, “Friendship for 54 Years”, in Amy Lanping Sung, Hu Kung-Chung Chien, editors, Shu Chien: Tributes on His 70th Birthday, World Scientific, page 38

adj

1. (normally said of a rope) Lax; not tense; not firmly extended.
   a slack rope
2. Weak; not holding fast.
   a slack hand
3. Moderate in some capacity.
   1. Moderately warm.
      a slack oven
   2. Moderate in speed.
      a slack wind
4. Lacking diligence or care; not earnest or eager.
   slack in duty or service
5. Not active or busy, successful, or violent.
   Business is slack.
   “They know our boats will stand up to their work,” said Willison, “and that counts for a good deal. A low estimate from us doesn't mean scamped work, but just for that we want to keep the yard busy over a slack time.” 1928, Lawrence R. Bourne, chapter 3, in Well Tackled!
   In the slack hours the service is maintained by single motor-coaches. 1940 December, “Notes and News: Waterloo & City Tube Modernisation”, in Railway Magazine, page 668
6. Excess; surplus to requirements.
   the slack capacity of an oil pipeline
7. (slang, Caribbean, Jamaica) Vulgar; sexually explicit, especially in dancehall music.
8. (linguistics) Lax.

adv

1. Slackly.
   slack dried hops

Etymology 2

From Middle English slakken, slaken, from Old English slacian, from Proto-Germanic *slakōną (“to slack, slacken”).

verb

1. (transitive, intransitive) To slacken.
2. (obsolete) To mitigate; to reduce the strength of.
3. To lose cohesion or solidity by a chemical combination with water; to slake.
   Lime slacks.

Etymology 3

Either from the adjective in Etymology 1 or the verb in Etymology 2.

noun

1. (rail transport) A temporary speed restriction where track maintenance or engineering work is being carried out at a particular place.
   This pitfall, beginning in February and finishing in May, resulted in a drop of about 3 ft. in the platform level; during this period it was necessary to level the track three times weekly, and impose a service slack of 15 m.p.h. The subsidence appears now to have finished, and normal speed is once again permitted. 1939 June, “Pertinent Paragraphs: Pitfalls”, in Railway Magazine, page 456
   The train runs slowly with frequent slacks for bridge and culvert repairs. At one point occurs the changeover from left- to right-hand running. 1949 September and October, “The "Nord Express"”, in Railway Magazine, page 336
   A 40 m.p.h. slack at West Ruislip, quickly followed by a 30 m.p.h. slack at Gerrards Cross, increased our lateness to four minutes at High Wycombe. 1960 February, R. C. Riley, “The London-Birmingham services - Past, Present and Future”, in Trains Illustrated, page 103

Etymology 4

From Middle English slak, from Old Norse slakki (“a slope”). Cognate with Icelandic slakki, Norwegian slakke.

noun

1. (countable) A valley, or small, shallow dell.

Etymology 5

Probably from German Schlacke (“dross, slag”). Doublet of slag.

noun

1. (mining) Small coal; coal dust.
   One of the important improvements of recent years has been attained by mixing the peat pulp as it passes through the grinding machine, with other inflammable materials, such as bituminous coal dust, or slack […] 1905, Colliery Engineer, volume 25, page 107
   It had rather a woolly and uneven beat and was inclined to prime, but there was no trouble with steaming even though the tender contained mostly small slack and dust. 1959 April, P. Ransome-Wallis, “The Southern in Trouble on the Kent Coast”, in Trains Illustrated, London: Ian Allan Publishing, →ISSN, →OCLC, page 220