[1] : The Collaborative International Dictionary of English v.0.48

slack \slack\, slacken \slack"en\, v. i. imp.  p. p.
   slacked, slackened; p. pr.  vb. n. slacking,
   slackening. see slack, a.
   1. to become slack; to be made less tense, firm, or rigid; to
      decrease in tension; as, a wet cord slackens in dry
      weather.
      1913 webster

   2. to be remiss or backward; to be negligent.
      1913 webster

   3. to lose cohesion or solidity by a chemical combination
      with water; to slake; as, lime slacks.
      1913 webster

   4. to abate; to become less violent.
      1913 webster

            whence these raging fires
            will slacken, if his breath stir not their flames.
                                                  --milton.
      1913 webster

   5. to lose rapidity; to become more slow; as, a current of
      water slackens.
      1913 webster

   6. to languish; to fail; to flag.
      1913 webster

   7. to end; to cease; to desist; to slake. obs.
      1913 webster

            that through your death your lineage should slack.
                                                  --chaucer.
      1913 webster

            they will not of that firste purpose slack.
                                                  --chaucer.
      1913 webster slack
see also:
slacked slackened slacking slackening slack 

[2] : WordNet (r) 2.0

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
see also:
relaxation loosening 

[3] : Moby Thesaurus II by Grady Ward, 1.0

74 moby thesaurus words for "slackening":
   abatement, allayment, alleviation, arrest, assuagement,
   attenuation, attrition, blunting, calming, check, damping,
   deadening, debilitation, deceleration, delay, demulsion, detention,
   devitalization, dilution, diminution, drag, dulcification, dulling,
   ease-off, ease-up, easing, effemination, enervation, enfeeblement,
   evisceration, exhaustion, extenuation, falling-off, fatigue,
   flagging, holdup, hushing, inanition, lag, languishment, leniency,
   lessening, letdown, letup, lightening, loosening, lulling,
   minus acceleration, mitigation, modulation, mollification,
   obstruction, pacification, palliation, quietening, quieting,
   reduction, relaxation, remission, retardation, retardment, setback,
   slack-up, slowdown, slowing, slowing down, slowup, softening,
   soothing, subduement, tempering, thinning, tranquilization,
   weakening

Slackening >> S Words
Slackening, definition of term: Slackening
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