slack

The part of anything that hangs loose, having no strain upon it.uncountable

• the slack of a rope or of a sail
• take in the slack

A dip in a surface.countableuncountable

• […] to make good the voids under the sleeper […] to take out "slacks" in the rail level […]

In particular, a shallow dell or hollow; a dip in the surface of terrain, such as between hills.countableuncountable

• Cauldstane Slap, or rather Slack, is a much frequented pass, through which the periodical droves of black cattle are transported into England.
• ... 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.

A low-lying marsh or a pool, especially a tidal or intermittent one which periodically fills and drains.countable

• 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[…]
• ... 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.

Forbearance; lenience; gracious allowance.uncountable

• cut [someone] some slack [= cut them a break]

Unconditional listening attention given by client to patient.uncountable

• 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."

Attributive form of slacks (“semi-formal trousers”).attributivecountableform-of

• 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.
• 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.

Lax; not tense; not firmly extended.

• a slack rope

Weak; not holding fast.

• a slack hand

Moderate in some capacity.; Moderately warm.

• a slack oven

Moderate in some capacity.; Moderate in speed.

• a slack wind

Lacking diligence or care; not earnest or eager.

• slack in duty or service

Not active or busy, successful, or violent.

• Business is slack.
• the slack period following the main tourist season

Excess; surplus to requirements.

• the slack capacity of an oil pipeline

Vulgar; sexually explicit, especially in dancehall music.CaribbeanJamaicaslang

Lax.

Slackly.not-comparable

• slack dried hops
• Her clothes hung slack on her.

To slacken.ambitransitive

• In this business of growing rich, poor men […] should slack their pace.

To mitigate; to reduce the strength of.obsolete

• Ne did ſhe let dull ſleepe once to relent, / Nor wearineſſe to ſlack her haſt, but fled / Euer alike,[…].

To lose cohesion or solidity by a chemical combination with water; to slake.

• Lime slacks.

To refuse to work as hard as one is supposed to.

• I can't afford to slack. This job is all I have!

A temporary speed restriction where track maintenance or engineering work is being carried out at a particular place.

• The train runs slowly with frequent slacks for bridge and culvert repairs. At one point occurs the changeover from left- to right-hand running.
• 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.

A valley, or small, shallow dell; a sag or saddle in a ridge.countable

• 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; […]
• "I see some folk coming through the slack yonder, […]"

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 (willow

Small coal; coal dust.uncountable

• 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 […]
• 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.