The Collaborative International Dictionary of English v.0.48:

Cruel \Cru"el\ (kr[udd]"[e^]l), n.
   See Crewel.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cruel \Cru"el\ (kr[udd]"[e^]l), a. [F. cruel, fr. L. crudelis,
   fr. crudus. See Crude.]
   1. Disposed to give pain to others; willing or pleased to
      hurt, torment, or afflict; destitute of sympathetic
      kindness and pity; savage; inhuman; hard-hearted;
      merciless.
      [1913 Webster]

            Behold a people cometh from the north country; . . .
            they are cruel and have no mercy.     --Jer. vi.
                                                  22,23.
      [1913 Webster]

   2. Causing, or fitted to cause, pain, grief, or misery.
      [1913 Webster]

            Cruel wars, wasting the earth.        --Milton.
      [1913 Webster]

            Cursed be their anger, for it was fierce; and their
            wrath for it was cruel.               --Gen. xlix.
                                                  7.
      [1913 Webster]

   3. Attended with cruetly; painful; harsh.
      [1913 Webster]

            You have seen cruel proof of this man's strength.
                                                  --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cruel
    adj 1: (of persons or their actions) able or disposed to inflict
           pain or suffering; "a barbarous crime"; "brutal
           beatings"; "cruel tortures"; "Stalin's roughshod
           treatment of the kulaks"; "a savage slap"; "vicious
           kicks" [syn: barbarous, brutal, cruel, fell,
           roughshod, savage, vicious]

Moby Thesaurus II by Grady Ward, 1.0:

129 Moby Thesaurus words for "cruel":
   Draconian, Tartarean, acute, afflictive, agonizing, animal,
   anthropophagous, atrocious, barbaric, barbarous, beastly, bestial,
   biting, bloodthirsty, bloody, bloody-minded, bowelless, brutal,
   brutalized, brute, brutish, callous, cannibalistic, cold-blooded,
   cramping, cruel-hearted, cruise, cutthroat, demoniac, demoniacal,
   devilish, diabolic, diabolical, distressing, dog-eat-dog,
   excruciating, fare, fell, feral, ferocious, fiendish, fiendlike,
   fierce, flinty, gnawing, go, gory, grave, grim, griping, hard,
   harrowing, harsh, heartless, heinous, hellish, hie, homicidal,
   hurtful, hurting, implacable, inclement, inexorable, infernal,
   inhuman, inhumane, journey, merciless, monstrous, murderous,
   outrageous, painful, paroxysmal, pass, piercing, pitiless,
   poignant, proceed, pungent, push on, racking, red-handed,
   relentless, remorseless, repair, ruthless, sadistic, sanguinary,
   sanguineous, satanic, savage, self-destructive, severe, sharkish,
   sharp, shooting, slaughterous, slavering, spasmatic, spasmic,
   spasmodic, stabbing, stinging, subhuman, suicidal, tormenting,
   torturous, travel, truculent, unchristian, uncivilized,
   uncompassionate, uncompassioned, unfeeling, unforgiving, unhuman,
   unkind, unmerciful, unpitiful, unpitying, unremorseful, unsparing,
   unsympathetic, unsympathizing, unyielding, vicious, wend,
   without mercy, wolfish