Source : Webster's Revised Unabridged Dictionary (1913)

Satanic \Sa*tan"ic\, Satanical \Sa*tan"ic*al\, a. [Cf. F.
   satanique, Gr. ?.]
   Of or pertaining to Satan; having the qualities of Satan;
   resembling Satan; extremely malicious or wicked; devilish;
   infernal. ``Satanic strength.'' ``Satanic host.'' --Milton.

         Detest the slander which, with a Satanic smile, exults
         over the character it has ruined.        --Dr. T.
                                                  Dwight.
   -- {Sa*tan"ic*al*ly}, adv. -- {Sa*tan"ic*al*ness}, n.

Source : WordNet®

satanic
     adj 1: extremely evil or cruel; expressive of cruelty or befitting
            hell; "something demonic in him--something that could
            be cruel"; "fires lit up a diabolic scene";
            "diabolical sorcerers under the influence of devils";
            "a fiendish despot"; "hellish torture"; "infernal
            instruments of war"; "satanic cruelty"; "unholy
            grimaces" [syn: {demonic}, {diabolic}, {diabolical}, {fiendish},
             {hellish}, {infernal}, {unholy}]
     2: of or relating to Satan; "Satanic verses"