The Collaborative International Dictionary of English v.0.48:

Release \Re*lease"\ (r?-l?s"), v. t. [imp. & p. p. Released
   (r?*l?st"); p. pr. & vb. n. Releasing.] [OE. relessen, OF.
   relassier, to release, to let free. See Relay, n., Relax,
   and cf. Release to lease again.]
   1. To let loose again; to set free from restraint,
      confinement, or servitude; to give liberty to, or to set
      at liberty; to let go.
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            Now at that feast he released unto them one
            prisoner, whomsoever they desired.    --Mark xv. 6.
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   2. To relieve from something that confines, burdens, or
      oppresses, as from pain, trouble, obligation, penalty.
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   3. (Law) To let go, as a legal claim; to discharge or
      relinquish a right to, as lands or tenements, by conveying
      to another who has some right or estate in possession, as
      when the person in remainder releases his right to the
      tenant in possession; to quit.
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   4. To loosen; to relax; to remove the obligation of; as, to
      release an ordinance. [Obs.] --Hooker.
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            A sacred vow that none should aye release.
                                                  --Spenser.
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   Syn: To free; liberate; loose; discharge; disengage;
        extricate; let go; quit; acquit.
        [1913 Webster]

WordNet (r) 3.0 (2006):

releasing
    adj 1: emotionally purging (of e.g. art) [syn: cathartic,
           releasing]