Etymology From Middle English slak, from Old English slæc (“slack”), from Proto-Germanic *slakaz. For sense of coal dust, compare slag.
1
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
A dip in a surface.
Richardson states that a low joint, a short distance from Haslam's Creek Bridge, was, in his opinion, the cause of the accident. […] [He] told Morgan, the Permanent Way Inspector, that there was a "slack" in the road on the Parramatta side of Haslam's Creek Bridge, […] I can positively state […] There was no such slack. The road was in as good running condition as I would wish to see any road. On all lines of course there are slacks, but not slacks of a serious nature; and that there was any such slack or depression in the rails as spoken of by Richardson I positively deny.1858, New South Wales. Parliament. Legislative Council, Votes & Proceedings, page 1020:
[…] a road may be kept up to approximately the same level at all times, and a fair surface maintained by rolling in large patches occasionally, as well as opening slacks in the road when they appear and effecting petty repairs. […] a series of slacks will begin to show in the run of the wheels; or […]1904, Public Works and Journal of Civil Engineering, page 90:
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[…] to make good the voids under the sleeper […] to take out "slacks" in the rail level […]1951, Institution of Civil Engineers (Great Britain), Proceedings of the Joint Engineering Conference, 1951, page 45:
3
In particular, a shallow dell or hollow; a dip in the surface of terrain, such as between hills.
Cauldstane Slap, or rather Slack, is a much frequented pass, through which the periodical droves of black cattle are transported into England.1815, Alexander Pennecuik, The Works of Alexander Pennecuik ...: Containing the Description of Tweeddale, and Miscellaneous Poems, page 141:
... for they had at that time observed the side of the brae, where the little green slack was situated, covered with a sheet of flame for a moment.1837, James Hogg, The hunt of Eildon. The adventures of Basil Lee. Adam Bell. Duncan Campbell. An old soldier's tale. Katie Cheyne. The long pack. A country funeral. The shepherd's calendar, page 249:
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Then she became a gay grey mare, / And stood in yonder slack; And he became a gilt saddle, / And sat upon her back.1845, Alexander Whitelaw, The Book of Scottish Ballads Collected and Illustrated with Historical and Critical Notices, London : Blackie, page 159:
Not that every mountain stream springs from a tarn, but almost every tarn sends out a stream. Then, tarn-hunting teaches the relatively position of places almost as exactly as do the mountain-tops, leading by "backs," and "shoulders," and "slacks," and "feet," and over the lower heights straight to half a dozen seemingly irreconcilable districts[…]1864, Elizabeth Lynn Linton, The Lake Country, page 172:
The great interest of the sandhills is the slacks. They are more frequent in some parts than in others, for there are miles where the hollows are all sand and stargrass. But every here and there the hills have receded and formed a little flat valley, where there is something like soil, and where the rain lodges and the mosses grow. This is a "slack;" and in the Lancashire slacks may be found some of the most beautiful […] flowers.1880, Littell's Living Age, page 448:
4
A low-lying marsh or a pool, especially a tidal or intermittent one which periodically fills and drains.
The "slacks" I have mentioned are fresh-water pools which extend just inside the outer sandhills. Being mostly dry in summer, the shore fowl love to breed there. Peewits nest on their banks, and the long grasses and sand willow[…]1901, The Pall Mall Magazine, page 138:
... in that quarter lay the great slack of the Watch Hill, the yellow slack that feeds the Blackburn, and in which horse and rider might readily disappear for ever.1983 [1897], Ernest Hamilton, The Outlaws of the Marches:
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Modern "moonpreneurs" now hijack tidal slacks to power server farms in Nova Scotia barns, mining Bitcoin during low tides when electricity costs crater.(Can we date this quote?), Conrad Riker, Fishing: A Comprehensive Exploration, Conrad Riker:
5
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:
6
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., →ISBN, page 7:
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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, →ISBN, page 38:
Normally said of a rope Lax; not tense; not firmly extended.
a slack rope
2
Weak; not holding fast.
a slack hand
› Moderate in some capacity.
3
Moderately warm.
a slack oven
4
Moderate in speed.
a slack wind
5
Lacking diligence or care; not earnest or eager.
slack in duty or service
The Lord is not ſlacke cõcerning his promiſe (as ſome men count ſlackneſſe)[…].1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC, 2 Peter 3:9, column 2:
6
Not active or busy, successful, or violent.
Business is slack.
the slack period following the main tourist season
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“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:
Etymology From Middle English slak, from Old English slæc (“slack”), from Proto-Germanic *slakaz. For sense of coal dust, compare slag.
1
Slackly.
slack dried hops
Her clothes hung slack on her.
slack
verb
Etymology From Middle English slakken, slaken, from Old English slacian, from Proto-Germanic *slakōną (“to slack, slacken”).
1
Ambitransitive To slacken.
I maruell I heare no nevves of Dromio, either hee ſlackes the matter, or betrayes his maiſter, I dare not motion anie thing to Stellio, till I knovve vvhat my boy hath don; Ile hunt him out, if the loiterſacke be gone ſpringing into a tauerne, Ile fetch him reeling out.c. 1590 (date written), [John Lyly], Mother Bombie. […], London: […] Thomas Scarlet for Cuthbert Burby, published 1594, →OCLC, Act II, scene ii, signature C3, verso:
In this business of growing rich, poor men […] should slack their pace.1692–1717, Robert South, Twelve Sermons Preached upon Several Occasions, volume (please specify |volume=I to VI), London:
Ne did ſhe let dull ſleepe once to relent, / Nor wearineſſe to ſlack her haſt, but fled / Euer alike,[…].1590, Edmund Spenser, “Book III, Canto VII”, in The Faerie Queene. […], London: […] [John Wolfe] for William Ponsonbie, →OCLC, stanza 2, page 494:
3
To lose cohesion or solidity by a chemical combination with water; to slake.
Etymology Either from the adjective in Etymology 1 or the verb in Etymology 2.
1
Rail transport, Railways, 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:
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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:
slack
noun
Etymology From Middle English slak, from Old Norse slakki (“a slope”). Cognate with Icelandic slakki, Norwegian slakke.
1
A valley, or small, shallow dell; a sag or saddle in a ridge.
Red Ringan sped, and the spearmen led, Up Goranberry Slack; Aye, many a wight, unmatched in fight, Who never more came back. And bloody set the westering sun, And bloody rose he up; […]1812, Walter Scott, Minstrelsy of the Scottish Border: Consisting of Historical and Romantic Ballads Collected in the Southern Counties of Scotland, with a Few of Modern Date Founded Upon Local Tradition, page 246:
"I see some folk coming through the slack yonder, […]"1871, Walter Scott, Waverly Novels, page 159:
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[…] southward, by the slack of the hill (2,500 feet), west of Ferrowie, (2,628 feet), on the County boundary, and descending by the Capel-burn to the South Esk,[…]1875, Alexander Smith, A New History of Aberdeenshire, page 690:
Sheelings : 1. Lies South of the Infields in a Slack betwixt two Hills 2. Lies at the South End of the Loch of Loch Beanoch […]1960, John Home, Survey of Assynt:
2
A flat-bottomed, hollow zone within a sand-dune system that has developed over impervious strata, sometimes due to erosion or blow-out of the dune system; its flat base level is therefore close to or at the permanent water-table level, and therefore has rich, marshy flora, with Salix species (willows) as typical woody colonisers.
slack
noun
Etymology Of unknown origin. Possibly related to Middle Dutch slacke or Middle Low German slecke. Doublet of slag.
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: