Source : Webster's Revised Unabridged Dictionary (1913)

Devilish \Dev"il*ish\, a.
   1. Resembling, characteristic of, or pertaining to, the
      devil; diabolical; wicked in the extreme. ``Devilish
      wickedness.'' --Sir P. Sidney.

            This wisdom descendeth not from above, but is
            earthly, sensual, devilish.           --James iii.
                                                  15.

   2. Extreme; excessive. [Colloq.] --Dryden.

   Syn: Diabolical; infernal; hellish; satanic; wicked;
        malicious; detestable; destructive. -- {Dev"il*ish*ly},
        adv. -- {Dev"il*ish*ness}, n.