[syn: madly, insanely, deadly, deucedly, devilishly]
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):
devilishly
    adv 1: as a devil; in an evil manner; "his writing could be
           diabolically satiric" [syn: diabolically, devilishly,
           fiendishly]
    2: 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]
    3: (used as intensives) extremely; "she was madly in love";
       "deadly dull"; "deadly earnest"; "deucedly clever"; "insanely
       jealous" [syn: madly, insanely, deadly, deucedly,
       devilishly]