Slack Slack·en v. i. [imp. & p. p. Slacked Slackened p. pr. & vb. n. Slacking, Slackening.]
 1. To become slack; to be made less tense, firm, or rigid; to decrease in tension; as, a wet cord slackens in dry weather.
 2. To be remiss or backward; to be negligent.
 3. To lose cohesion or solidity by a chemical combination with water; to slake; as, lime slacks.
 4. To abate; to become less violent.
 Whence these raging fires
 Will slacken, if his breath stir not their flames.   --Milton.
 5. To lose rapidity; to become more slow; as, a current of water slackens.
 6. To languish; to fail; to flag.
 7. To end; to cease; to desist; to slake. [Obs.]
    That through your death your lineage should slack.   --Chaucer.
    They will not of that firste purpose slack.   --Chaucer.
 slackening
      n : an occurrence of control or strength weakening; "the
          relaxation of requirements"; "the loosening of his grip";
          "the slackening of the wind" [syn: relaxation, loosening]