Source : Webster's Revised Unabridged Dictionary (1913)

Loosen \Loos"en\, v. t. [imp. & p. p. {Loosened}; 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.

            After a year's rooting, then shaking doth the tree
            good by loosening of the earth.       --Bacon.

   2. To free from restraint; to set at liberty..

            It loosens his hands, and assists his understanding.
                                                  --Dryden.

   3. To remove costiveness from; to facilitate or increase the
      alvine discharges of. --Bacon.

Source : WordNet®

loosening
     n 1: an occurrence of control or strength weakening; "the
          relaxation of requirements"; "the loosening of his
          grip"; "the slackening of the wind" [syn: {relaxation},
          {slackening}]
     2: the act of making something less tight [syn: {laxation}]
        [ant: {tightening}]