The Collaborative International Dictionary of English v.0.48:

Abandon \A*ban"don\ ([.a]*b[a^]n"d[u^]n), v. t. [imp. & p. p.
   Abandoned (-d[u^]nd); p. pr. & vb. n. Abandoning.] [OF.
   abandoner, F. abandonner; a (L. ad) + bandon permission,
   authority, LL. bandum, bannum, public proclamation,
   interdiction, bannire to proclaim, summon: of Germanic
   origin; cf. Goth. bandwjan to show by signs, to designate
   OHG. ban proclamation. The word meant to proclaim, put under
   a ban, put under control; hence, as in OE., to compel,
   subject, or to leave in the control of another, and hence, to
   give up. See Ban.]
   1. To cast or drive out; to banish; to expel; to reject.
      [Obs.]
      [1913 Webster]

            That he might . . . abandon them from him. --Udall.
      [1913 Webster]

            Being all this time abandoned from your bed. --Shak.
      [1913 Webster]

   2. To give up absolutely; to forsake entirely; to renounce
      utterly; to relinquish all connection with or concern on;
      to desert, as a person to whom one owes allegiance or
      fidelity; to quit; to surrender.
      [1913 Webster]

            Hope was overthrown, yet could not be abandoned.
                                                  --I. Taylor.
      [1913 Webster]

   3. Reflexively: To give (one's self) up without attempt at
      self-control; to yield (one's self) unrestrainedly; --
      often in a bad sense.
      [1913 Webster]

            He abandoned himself . . . to his favorite vice.
                                                  --Macaulay.
      [1913 Webster]

   4. (Mar. Law) To relinquish all claim to; -- used when an
      insured person gives up to underwriters all claim to the
      property covered by a policy, which may remain after loss
      or damage by a peril insured against.
      [1913 Webster]

   Syn: To give up; yield; forego; cede; surrender; resign;
        abdicate; quit; relinquish; renounce; desert; forsake;
        leave; retire; withdraw from.

   Usage: To Abandon, Desert, Forsake. These words agree
          in representing a person as giving up or leaving some
          object, but differ as to the mode of doing it. The
          distinctive sense of abandon is that of giving up a
          thing absolutely and finally; as, to abandon one's
          friends, places, opinions, good or evil habits, a
          hopeless enterprise, a shipwrecked vessel. Abandon is
          more widely applicable than forsake or desert. The
          Latin original of desert appears to have been
          originally applied to the case of deserters from
          military service. Hence, the verb, when used of
          persons in the active voice, has usually or always a
          bad sense, implying some breach of fidelity, honor,
          etc., the leaving of something which the person should
          rightfully stand by and support; as, to desert one's
          colors, to desert one's post, to desert one's
          principles or duty. When used in the passive, the
          sense is not necessarily bad; as, the fields were
          deserted, a deserted village, deserted halls. Forsake
          implies the breaking off of previous habit,
          association, personal connection, or that the thing
          left had been familiar or frequented; as, to forsake
          old friends, to forsake the paths of rectitude, the
          blood forsook his cheeks. It may be used either in a
          good or in a bad sense.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Abandoned \A*ban"doned\ ([.a]*b[a^]n"d[u^]nd), a.
   1. Forsaken, deserted. "Your abandoned streams." --Thomson.
      [1913 Webster]

   2. Self-abandoned, or given up to vice; extremely wicked, or
      sinning without restraint; irreclaimably wicked; as, an
      abandoned villain.
      [1913 Webster]

   Syn: Profligate; dissolute; corrupt; vicious; depraved;
        reprobate; wicked; unprincipled; graceless; vile.

   Usage: Abandoned, Profligate, Reprobate. These
          adjectives agree in expressing the idea of great
          personal depravity. Profligate has reference to open
          and shameless immoralities, either in private life or
          political conduct; as, a profligate court, a
          profligate ministry. Abandoned is stronger, and
          has reference to the searing of conscience and
          hardening of heart produced by a man's giving himself
          wholly up to iniquity; as, a man of abandoned
          character. Reprobate describes the condition of one
          who has become insensible to reproof, and who is
          morally abandoned and lost beyond hope of recovery.
          [1913 Webster]

                God gave them over to a reprobate mind. --Rom.
                                                  i. 28.
          [1913 Webster]

WordNet (r) 3.0 (2006):

abandoned
    adj 1: forsaken by owner or inhabitants ; "weed-grown yard of an
           abandoned farmhouse" [syn: abandoned, derelict,
           deserted]
    2: free from constraint; "an abandoned sadness born of grief"-
       Liam O'Flaherty

Moby Thesaurus II by Grady Ward, 1.0:

296 Moby Thesaurus words for "abandoned":
   a bit much, abjured, afire, amok, antiquated, antique, archaic,
   ardent, available, bellowing, berserk, boundless, burning,
   carried away, cast-off, castaway, ceded, committed, contaminated,
   corrupt, corrupted, debased, debauched, decadent, dedicated,
   defenseless, degenerate, degraded, delirious, demoniac, depraved,
   derelict, deserted, desolate, devoted, devout, discarded,
   discontinued, disowned, dispensed with, disposed of, disregarded,
   dissipated, dissolute, distracted, disused, done with, earnest,
   ecstatic, egregious, enormous, enraptured, exaggerated, excessive,
   exorbitant, extravagant, extreme, fabulous, faithful, fancy, fast,
   fatherless, feral, ferocious, fervent, fervid, fierce, fiery,
   flaming, forgone, forlorn, forsaken, forsworn, frantic, free,
   frenzied, friendless, fulminating, furious, gallant, gay, gigantic,
   gluttonous, go-go, godforsaken, haggard, half-done, hearty, heated,
   helpless, high, hog-wild, homeless, hot, hot-blooded, howling,
   hyperbolic, hypertrophied, hysterical, ignored, immoderate,
   impassioned, in a transport, in earnest, in hysterics, incontinent,
   incorrigible, indulgent, inordinate, intemperate, intense, intent,
   intent on, intoxicated, irrepressible, jettisoned, kithless,
   laid aside, lascivious, lax, lecherous, left, left undone, lewd,
   licentious, loose, lost to shame, loyal, mad, madding, maniac,
   marooned, missed, monstrous, morally polluted, motherless,
   neglected, nonrestrictive, not worth saving, obsolescent, obsolete,
   old, old-fashioned, omitted, on fire, on the shelf, open, orgasmic,
   orgiastic, out, out of bounds, out of control, out of hand,
   out of sight, out of use, out-of-date, outcast, outdated, outmoded,
   outrageous, outside the gates, outside the pale, outworn, overbig,
   overdeveloped, overgreat, overgrown, overlarge, overlooked,
   overmuch, overweening, passed by, passed over, passed up,
   passionate, past use, pensioned off, perfervid, permissive,
   perverted, pigeonholed, polluted, possessed, profligate, put aside,
   rabid, raging, rakehell, rakehellish, rakehelly, rakish, rampant,
   ramping, ranting, raving, ravished, recanted, red-hot, reinless,
   rejected, released, relinquished, renounced, reprobate, resigned,
   resolute, retired, retracted, riotous, roaring, rotten,
   running mad, sacrificed, serious, shunted, sidelined, sidetracked,
   sincere, slighted, solitary, spirited, steep, steeped in iniquity,
   stiff, storming, superannuate, superannuated, superseded,
   surrendered, tainted, tenantless, too much, transported, unasked,
   unattended to, unbridled, uncared-for, unchaperoned, unchecked,
   uncoerced, uncompelled, unconscionable, unconsidered,
   unconstrained, uncontrollable, uncontrolled, uncouth, uncurbed,
   undone, undue, unfilled, unforced, unfriended, ungoverned,
   uninhabited, uninhibited, unmanned, unmastered, unmeasured,
   unmuzzled, unoccupied, unpeopled, unpopulated, unprincipled,
   unreasonable, unregarded, unreined, unrepressed, unreserved,
   unrestrained, unrestrictive, unruly, unsolicited, unstaffed,
   unsubdued, unsuppressed, untaken, untenanted, untended, unwatched,
   vacant, vehement, vice-corrupted, violent, vitiated, waived,
   wanton, warm, warped, white-hot, wild, wild-eyed, wild-looking,
   worn-out, yielded, zealous