[syn: devilishly, devilish]
The Collaborative International Dictionary of English v.0.48:
Devilish \Dev"il*ish\, a.
   1. Resembling, characteristic of, or pertaining to, the
      devil; diabolical; wicked in the extreme. "Devilish
      wickedness." --Sir P. Sidney.
      [1913 Webster]
            This wisdom descendeth not from above, but is
            earthly, sensual, devilish.           --James iii.
                                                  15.
      [1913 Webster]
   2. Extreme; excessive. [Colloq.] --Dryden.
   Syn: Diabolical; infernal; hellish; satanic; wicked;
        malicious; detestable; destructive. -- Dev"il*ish*ly,
        adv. -- Dev"il*ish*ness, n.
        [1913 Webster]
WordNet (r) 3.0 (2006):
devilish
    adv 1: in a playfully devilish manner; "the socialists are
           further handicapped if they believe that capitalists are
           not only wicked but also devilishly clever" [syn:
           devilishly, devilish]
    adj 1: showing the cunning or ingenuity or wickedness typical of
           a devil; "devilish schemes"; "the cold calculation and
           diabolic art of some statesmen"; "the diabolical
           expression on his face"; "a mephistophelian glint in his
           eye" [syn: devilish, diabolic, diabolical,
           mephistophelian, mephistophelean]
    2: playful in an appealingly bold way; "a roguish grin" [syn:
       devilish, rascally, roguish]
Moby Thesaurus II by Grady Ward, 1.0:
114 Moby Thesaurus words for "devilish":
   Acherontic, Draconian, Lethean, Mephistophelian, Plutonian,
   Plutonic, Stygian, Tartarean, accursed, animal, anthropophagous,
   arch, atrocious, bad, barbaric, barbarous, beastly, bestial,
   bloodthirsty, bloody, bloody-minded, brutal, brutalized, brute,
   brutish, cannibalistic, chthonian, chthonic, crazy, cruel,
   cruel-hearted, cursed, damnable, demoniac, demoniacal, demonic,
   demonish, demonlike, devil-like, diabolic, diabolical, elfish,
   elvish, evil, execrable, fell, feral, ferocious, fiendish,
   fiendlike, fierce, flagitious, foolish, full of mischief, ghoulish,
   heinous, hellborn, hellish, high-spirited, impish, infernal,
   inhuman, inhumane, iniquitous, knavish, madcap, maleficent,
   malevolent, malign, malignant, mischief-loving, mischievous,
   murderous, naughty, nefarious, ogreish, pandemoniac, pandemonic,
   playful, prankish, pranksome, pranky, puckish, purgatorial,
   roguish, ruthless, sadistic, sanguinary, sanguineous, satanic,
   savage, scampish, scapegrace, serpentine, sharkish, sinful,
   sinister, slavering, sportive, subhuman, sulfurous, trickish,
   tricksy, truculent, unchristian, uncivilized, ungodly, unhallowed,
   unhuman, vicious, villainous, waggish, wicked, wolfish