The Collaborative International Dictionary of English v.0.48:

Flagrant \Fla"grant\, a. [L. flagrans, -antis, p. pr. of
   flagrate to burn, akin to Gr. ?: cf. F. flagrant. Cf.
   Flame, Phlox.]
   1. Flaming; inflamed; glowing; burning; ardent.
      [1913 Webster]

            The beadle's lash still flagrant on their back.
                                                  --Prior.
      [1913 Webster]

            A young man yet flagrant from the lash of the
            executioner or the beadle.            --De Quincey.
      [1913 Webster]

            Flagrant desires and affections.      --Hooker.
      [1913 Webster]

   2. Actually in preparation, execution, or performance;
      carried on hotly; raging.
      [1913 Webster]

            A war the most powerful of the native tribes was
            flagrant.                             --Palfrey.
      [1913 Webster]

   3. Flaming into notice; notorious; enormous; heinous;
      glaringly wicked.

   Syn: Atrocious; flagitious; glaring. See Atrocious.
        [1913 Webster]

WordNet (r) 3.0 (2006):

flagrant
    adj 1: conspicuously and outrageously bad or reprehensible; "a
           crying shame"; "an egregious lie"; "flagrant violation of
           human rights"; "a glaring error"; "gross ineptitude";
           "gross injustice"; "rank treachery" [syn: crying(a),
           egregious, flagrant, glaring, gross, rank]

Moby Thesaurus II by Grady Ward, 1.0:

247 Moby Thesaurus words for "flagrant":
   abject, ablaze, abominable, absolute, afire, aflame, aflicker,
   aglow, alight, ardent, arrant, atrocious, audacious, awful, bad,
   barefaced, base, beastly, beggarly, beneath contempt, black,
   blamable, blameworthy, blatant, blazing, bold, brazen, brazenfaced,
   brutal, burning, candent, candescent, capital, cheesy, classical,
   colorful, comburent, complete, conflagrant, conspicuous,
   consummate, contemptible, contemptuous, crass, criminal, crude,
   cruel, crummy, damnable, dark, debased, decided, defiant,
   definitive, degraded, deplorable, depraved, despicable, detestable,
   dire, dirty, disgraceful, disgusting, downright, dreadful,
   egregious, enormous, evil, execrable, exhibitionistic, extravagant,
   fetid, filthy, flagitious, flaming, flaring, flaunting, flickering,
   forward, foul, fulsome, fuming, garish, gaudy, glaring, glowing,
   gorgeous, grave, grievous, gross, guttering, hanging out, hateful,
   heinous, horrible, horrid, ignescent, ignited, immodest, improper,
   in a blaze, in a glow, in flames, in relief, in the foreground,
   incandescent, inconsiderate, infamous, inflamed, iniquitous,
   intolerable, kindled, knavish, lamentable, little, live, living,
   loathsome, loud, lousy, low, low-down, lumpen, lurid, mangy, mean,
   measly, meretricious, miserable, monstrous, nasty, naughty,
   nefarious, noisome, notable, noticeable, notorious, obnoxious,
   obtrusive, obvious, odious, offensive, on fire, open, ostensible,
   out-and-out, outrageous, outright, outstanding, paltry, peccant,
   perfect, petty, pitiable, pitiful, poky, poor, positive, precious,
   profound, prominent, pronounced, proper, rank, reeking,
   regrettable, regular, reprehensible, reprobate, reptilian,
   repulsive, rotten, sad, salient, scabby, scandalous, schlock,
   scintillant, scintillating, scornful, screaming, scrubby, scruffy,
   scummy, scurvy, sensational, shabby, shameful, shameless,
   shattering, shocking, shoddy, sinful, small, smoking, smoldering,
   sordid, sparking, spectacular, squalid, staring, stark,
   stark-staring, sticking out, striking, superlative, surpassing,
   tawdry, terrible, the veriest, thorough, thoroughgoing, too bad,
   total, treacherous, unabashed, unashamed, unbearable, unblushing,
   unclean, unconscionable, undeniable, unembarrassed, unequivocal,
   unextinguished, unforgivable, unmentionable, unmitigated, unmodest,
   unpardonable, unqualified, unquenched, unrelieved, unspeakable,
   unspoiled, unworthy, utter, vicious, vile, villainous, vulgar,
   wicked, woeful, worst, worthless, wretched, wrong