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]