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]