The Collaborative International Dictionary of English v.0.48:

Derelict \Der"e*lict\, a. [L. derelictus, p. p. of derelinquere
   to forsake wholly, to abandon; de- + relinquere to leave. See
   Relinquish.]
   1. Given up or forsaken by the natural owner or guardian;
      left and abandoned; as, derelict lands.
      [1913 Webster]

            The affections which these exposed or derelict
            children bear to their mothers, have no grounds of
            nature or assiduity but civility and opinion. --Jer.
      Taylor.
      [1913 Webster]

   2. Lost; adrift; hence, wanting; careless; neglectful;
      unfaithful.
      [1913 Webster]

            They easily prevailed, so as to seize upon the
            vacant, unoccupied, and derelict minds of his
            [Chatham's] friends; and instantly they turned the
            vessel wholly out of the course of his policy.
                                                  --Burke.
      [1913 Webster]

            A government which is either unable or unwilling to
            redress such wrongs is derelict to its highest
            duties.                               --J. Buchanan.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Derelict \Der"e*lict\, n. (Law)
      (a) A thing voluntary abandoned or willfully cast away by
          its proper owner, especially a ship abandoned at sea.
      (b) A tract of land left dry by the sea, and fit for
          cultivation or use.
          [1913 Webster]

WordNet (r) 3.0 (2006):

derelict
    adj 1: worn and broken down by hard use; "a creaky shack"; "a
           decrepit bus...its seats held together with friction
           tape"; "a flea-bitten sofa"; "a run-down neighborhood";
           "a woebegone old shack" [syn: creaky, decrepit,
           derelict, flea-bitten, run-down, woebegone]
    2: forsaken by owner or inhabitants ; "weed-grown yard of an
       abandoned farmhouse" [syn: abandoned, derelict,
       deserted]
    3: failing in what duty requires; "derelict (or delinquent) in
       his duty"; "neglectful of his duties"; "remiss of you not to
       pay your bills" [syn: derelict, delinquent, neglectful,
       remiss]
    4: in deplorable condition; "a street of bedraggled tenements";
       "a broken-down fence"; "a ramshackle old pier"; "a tumble-
       down shack" [syn: bedraggled, broken-down, derelict,
       dilapidated, ramshackle, tatterdemalion, tumble-down]
    n 1: a person without a home, job, or property
    2: a ship abandoned on the high seas [syn: abandoned ship,
       derelict]

Moby Thesaurus II by Grady Ward, 1.0:

174 Moby Thesaurus words for "derelict":
   Bowery bum, DP, Ishmael, abandoned, battered, beachcomber, beat-up,
   beaten up, beggar, beggarly fellow, behindhand, blighter,
   broken-down, budmash, bum, bummer, caitiff, careless, cast-off,
   castaway, castoff, culpably negligent, declasse, decrepit,
   delinquent, deserted, desolate, devil, dilapidated, dilatory,
   dingy, disaffected, discard, discarded, disloyal, disowned,
   displaced person, disregardful, disused, dogie, down-and-out,
   drifter, drunkard, evictee, exile, expatriate, expellee, faded,
   faithless, false, fickle, floater, flotsam, flotsam and jetsam,
   forsaken, foundling, good-for-naught, good-for-nothing, heedless,
   hobo, human wreck, in ruins, inadvertent, inattentive, inconstant,
   irresponsible, jetsam, jettisoned, junk, lagan, laissez-faire, lax,
   lazzarone, left, leper, loafer, loose, lowlife, malingerer,
   marooned, mauvais sujet, mean wretch, mucker, neglected,
   neglectful, neglecting, negligent, no-good, noninterfering,
   nonrestrictive, not true to, of bad faith, off-guard, orphan,
   outcast, outcast of society, outcaste, outlaw, outside the gates,
   outside the pale, overly permissive, pariah, pauvre diable,
   permissive, persona non grata, pilgarlic, poor creature,
   poor devil, procrastinating, ramshackle, recreant, refuse,
   regardless, reject, rejected, relaxed, remiss, rubbish, ruined,
   ruinous, run-down, sad case, sad sack, scamping, seedy, shabby,
   skid-row bum, skimping, slack, slacker, slighting, slipshod,
   sloppy, slovenly, slummy, slurring, social outcast, solitary,
   stiff, street arab, sundowner, swagman, threadbare, tottery, tramp,
   trash, trothless, truant, tumbledown, unacceptable person,
   uncircumspect, uncouth, undependable, undesirable, unfaithful,
   unguarded, unloyal, unreliable, unrigorous, unsteadfast,
   untouchable, untrue, untrustworthy, unwary, unwatchful, vag,
   vagabond, vagrant, vaurien, waif, waifs and strays, wastrel,
   worthless fellow, wretch



Bouvier's Law Dictionary, Revised 6th Ed (1856):

DERELICT, common law. This term is applied in the common law in a different
sense from what it bears in the civil law. In the former it is applied to
lands left by the sea.
     2. When so left by degrees the derelict land belongs to the owner of
the soil adjoining but when the sea retires suddenly, it belongs to the
government. 2 Bl. Com. 262 1 Bro. Civ. Law, 239; 1 Sumn. 328, 490 1 Gallis.
138; Bee, R. 62, 178, 260; Ware, R. 332.