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

loosen \loos"en\, v. i.
   to become loose; to become less tight, firm, or compact. --s.
   sharp.
   1913 webster

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

loosen \loos"en\ l=oos"'n, v. t. imp.  p. p. loosened
   l=oos"'nd; p. pr.  vb. n. loosening. see loose, v.
   t.
   1. to make loose; to free from tightness, tension, firmness,
      or fixedness; to make less dense or compact; as, to loosen
      a string, or a knot; to loosen a rock in the earth.
      1913 webster

            after a year's rooting, then shaking doth the tree
            good by loosening of the earth.       --bacon.
      1913 webster

   2. to free from restraint; to set at liberty..
      1913 webster

            it loosens his hands, and assists his understanding.
                                                  --dryden.
      1913 webster

   3. to remove costiveness from; to facilitate or increase the
      alvine discharges of. --bacon.
      1913 webster
see also:
loosened loosening loose 

[3] : WordNet (r) 2.0

loosen
     v 1: make loose or looser; "loosen the tension on a rope" syn: loose
          ant: stiffen
     2: make less severe or strict; "the government relaxed the
        curfew after most of the rebels were caught" syn: relax
     3: become less severe or strict; "the rules relaxed after the
        new director arrived" syn: relax
     4: disentangle and raise the fibers of; "tease wool" syn: tease,
         tease apart
     5: cause to become loose; "undo the shoelace"; "untie the
        knot"; "loosen the necktie" syn: untie, undo
     6: make less dense; "loosen the soil"
     7: become loose or looser or less tight; "the noose loosened";
        "the rope relaxed" syn: relax, loose ant: stiffen
see also:
loose stiffen relax tease tease apart untie 
undo 

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

105 moby thesaurus words for "loosen":
   abate, bate, cast off, cushion, cut apart, detach, diffuse,
   discharge, disengage, disenthrall, disjoin, disperse, doff, ease,
   ease off, ease up, emancipate, fluff, free, gentle, knead, lax,
   laxate, let down, let go, let up, liberate, limber, limber up,
   loose, manumit, mash, massage, mellow, milden, mitigate, mollify,
   plump, pulp, relax, release, remit, remove, scatter, separate,
   sever, shake up, slack, slack off, slack up, slacken, slake, smash,
   soften, soften up, squash, subdue, supple, take off, tenderize,
   tone down, tune down, unbar, unbend, unbind, unbolt, unbrace,
   unbridle, unbuckle, unbutton, uncage, unchain, unclasp, undo,
   unfasten, unfetter, ungag, unglue, unhandcuff, unhobble, unhook,
   unlace, unlash, unlatch, unleash, unlock, unloose, unloosen,
   unmanacle, unmuzzle, unpen, unpinion, unscrew, unshackle, unstick,
   unstrain, unstrap, unstring, untether, untie, untighten, untruss,
   unyoke, weaken, weigh anchor

Loosen >> L Words
Loosen, definition of term: Loosen
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