The Collaborative International Dictionary of English v.0.48:

Philippic \Phi*lip"pic\, n. [L. Philippiko`s belonging to
   Philip, Philippic, Gr. filippikos, fr. Fi`lippos Philip,
   fi`lippos fond of horses: cf. F. philippique.]
   1. Any one of the series of famous orations of Demosthenes,
      the Grecian orator, denouncing Philip, king of Macedon.
      [1913 Webster]

   2. Hence: Any discourse or declamation abounding in
      acrimonious invective.
      [1913 Webster]

WordNet (r) 3.0 (2006):

philippic
    n 1: a speech of violent denunciation [syn: tirade,
         philippic, broadside]