The Collaborative International Dictionary of English v.0.48:

Reprobate \Rep"ro*bate\ (-b?t), a. [L. reprobatus, p. p. of
   reprobare to disapprove, condemn. See Reprieve, Reprove.]
   [1913 Webster]
   1. Not enduring proof or trial; not of standard purity or
      fineness; disallowed; rejected. [Obs.]
      [1913 Webster]

            Reprobate silver shall men call them, because the
            Lord hath rejected them.              --Jer. vi. 30.
      [1913 Webster]

   2. Abandoned to punishment; hence, morally abandoned and
      lost; given up to vice; depraved.
      [1913 Webster]

            And strength, and art, are easily outdone
            By spirits reprobate.                 --Milton.
      [1913 Webster]

   3. Of or pertaining to one who is given up to wickedness; as,
      reprobate conduct. "Reprobate desire." --Shak.
      [1913 Webster]

   Syn: Abandoned; vitiated; depraved; corrupt; wicked;
        profligate; base; vile. See Abandoned.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Reprobate \Rep"ro*bate\, n.
   One morally abandoned and lost.
   [1913 Webster]

         I acknowledge myself for a reprobate, a villain, a
         traitor to the king.                     --Sir W.
                                                  Raleigh.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Reprobate \Rep"ro*bate\ (-b?t), v. t. [imp. & p. p. Reprobated
   (-b?`t?d); p. pr. & vb. n. Reprobating.]
   1. To disapprove with detestation or marks of extreme
      dislike; to condemn as unworthy; to disallow; to reject.
      [1913 Webster]

            Such an answer as this is reprobated and disallowed
            of in law; I do not believe it, unless the deed
            appears.                              --Ayliffe.
      [1913 Webster]

            Every scheme, every person, recommended by one of
            them, was reprobated by the other.    --Macaulay.
      [1913 Webster]

   2. To abandon to punishment without hope of pardon.
      [1913 Webster]

   Syn: To condemn; reprehend; censure; disown; abandon; reject.
        [1913 Webster]

WordNet (r) 3.0 (2006):

reprobate
    adj 1: deviating from what is considered moral or right or
           proper or good; "depraved criminals"; "a perverted sense
           of loyalty"; "the reprobate conduct of a gambling
           aristocrat" [syn: depraved, perverse, perverted,
           reprobate]
    n 1: a person without moral scruples [syn: reprobate,
         miscreant]
    v 1: reject (documents) as invalid [ant: approbate]
    2: abandon to eternal damnation; "God reprobated the unrepenting
       sinner"
    3: express strong disapproval of; "We condemn the racism in
       South Africa"; "These ideas were reprobated" [syn: condemn,
       reprobate, decry, objurgate, excoriate]

Moby Thesaurus II by Grady Ward, 1.0:

173 Moby Thesaurus words for "reprobate":
   abandoned, abominable, accursed, accuse, amoral, anathematize,
   anathemize, animadvert on, arraign, arrant, atrocious, backslider,
   bad, bad egg, bad lot, base, bastard, black, black sheep,
   blackguard, blackguardly, blamable, blame, blameworthy,
   call to account, cast blame upon, cast reflection upon, censure,
   complain against, condemn, contaminated, corrupt, corrupted,
   criminal, cry down, cry out against, cry out on, cry shame upon,
   cur, cursed, damn, damnable, damned, dark, debased, debauched,
   debauchee, decadent, decry, degenerate, degraded, denounce,
   denunciate, depraved, despicable, disapprove, disgraceful, dismiss,
   dissolute, evil, execrable, fallen angel, flagitious, flagrant,
   fleshly, foul, fulminate against, godless, good-for-nothing,
   graceless, heel, heinous, immoral, impeach, improper, impugn,
   indict, infamous, iniquitous, inveigh against, irredeemable, knave,
   knavish, knock, lecher, libertine, licentious, lost, lost sheep,
   lost soul, low, lowlife, mean, miscreant, monstrous,
   morally polluted, mundane, naughty, nefarious, nonsacred,
   notorious, peccant, pervert, perverted, pimp, polluted, profane,
   profligate, rake, rank, rap, rapscallion, rascal, rascally,
   recidivist, recreant, reflect upon, refuse, reject, reprehend,
   reprehensible, reproach, repudiate, roguish, rotten, roue,
   scalawag, scamp, scampish, scandalous, scapegrace, scoundrel,
   scoundrelly, secular, shake up, shameful, shameless, shriftless,
   sinful, skin, sorry lot, spurn, steeped in iniquity, tainted,
   temporal, trollop, turn down, unblessed, unconverted, unforgivable,
   unhallowed, unholy, unpardonable, unprincipled, unredeemed,
   unregenerate, unsacred, unsanctified, unspeakable, unworthy,
   vice-corrupted, vicious, vile, villain, villainous, vitiated,
   warped, wastrel, whore, wicked, worldly, wretch, wrong



Easton's 1897 Bible Dictionary:

Reprobate
   that which is rejected on account of its own worthlessness (Jer.
   6:30; Heb. 6:8; Gr. adokimos, "rejected"). This word is also
   used with reference to persons cast away or rejected because
   they have failed to make use of opportunities offered them (1
   Cor. 9:27; 2 Cor. 13:5-7).