To become less tense, firm or rigid; to decrease in tension; as, a wet cord slackens in dry weather.

To be remiss or backward; to neglect. Deuteronomy 23:21.

To lose cohesion or the quality of adhesion; as, lime slacks and crumbles into power.

To abate; to become less violent. Whence these raging fires will slacken, if his breath stir not their flames.

To lose rapidity; to become more slow; as, a current of water slackens; the tide slackens.

To languish; to fail; to flag.

To lessen tension; to make less tense or tight; as, to slacken a rope or a bandage.

To relax; to remit; as, to slacken exertion or labor.

To mitigate; to diminish in severity; as, to slacken pain.

To become more slow; to lessen rapidity; as, to slacken one’s pace.

To abate; to lower; as, to slacken the heat of a fire.

To relieve; to unbend; to remit; as, to slacken cares.

To withhold; to use less liberally.

To deprive or cohesion; as, to slack lime.

To repress; to check. I should be griev’d young prince, to think my presence unbent you thoughts and slacken’d ‘em to arms.

To neglect. Slack not the good presage.

To repress, or make less quick or active.

Among miners, a spungy semi-vitrified substance which they mix with the ores of metals to prevent their fusion.