slack

A soft wet area of low-lying land that sinks underfoot.

A cord or rope or cable that is hanging loosely.

“he took up the slack”

Dust consisting of a mixture of small coal fragments and coal dust and dirt that sifts out when coal is passed over a sieve.

A stretch of water without current or movement.

“suddenly they were in a slack and the water was motionless”

The quality of being loose (not taut).

“he hadn't counted on the slackness of the rope”

A noticeable deterioration in performance or quality.

“a gradual slack in output”

Make less active or intense.

Avoid responsibilities and work, be idle.

Be inattentive to, or neglect.

“He slacks his attention”

Release tension on.

“slack the rope”

Make less active or fast.

“He slackened his pace as he got tired”

Cause to heat and crumble by treatment with water.

“slack lime”

Become slow or slower.

Become less in amount or intensity.

Lacking in rigor or strictness.

“slack in maintaining discipline”

Flowing with little speed as e.g. at the turning of the tide.

“slack water”

Not tense or taut.

“slack and wrinkled skin”

“slack sails”