Slacken

Slacken is a verb meaning to make or become looser or less taut. It is used for physical tension, such as slackening a rope, belt, chain, or line, where the aim is to reduce tension and allow give. It is also used figuratively to describe reducing intensity, pace, or effort, for example slackening the pace of work or slackening enforcement of rules.

Grammatically, slacken can be transitive (slacken the rope) or intransitive (the rope slackens). The common phrasal variant slacken off or slack off describes easing up or reducing effort, discipline, or activity. The noun form slack refers to the state of looseness or lack of tension, though it is more often encountered as an adjective or in other senses.

In specialized contexts, slacken is used in engineering and construction to describe relaxing tension on mechanical elements such as belts, chains, or guy lines, and in nautical usage to describe a line that has lost tension. In sports or physical training, to slacken may describe letting up on exertion or relaxing grip.

Etymology: Slacken is formed from the adjective slack, meaning loose, with the suffix -en to form a verb. The sense of reducing tension is well established in English usage from Middle English to the present.