Source : WordNet®

the Devil
     n 1: (Judeo-Christian and Islamic religions) chief spirit of evil
          and adversary of God; tempter of mankind; master of Hell
          [syn: {Satan}, {Old Nick}, {Devil}, {Lucifer}, {Beelzebub},
           {the Tempter}, {Prince of Darkness}]
     2: something difficult or awkward to do or deal with; "it will
        be the devil to solve"