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]

Moby Thesaurus II by Grady Ward, 1.0:

62 Moby Thesaurus words for "philippic":
   abuse, address, after-dinner speech, allocution, assailing,
   assault, attack, berating, bitter words, blackening, chalk talk,
   contumely, debate, declamation, diatribe, eulogy, execration,
   exhortation, filibuster, forensic, forensic address, formal speech,
   funeral oration, harangue, hard words, hortatory address,
   inaugural, inaugural address, invective, jawing, jeremiad,
   onslaught, oration, pep talk, peroration, pitch, prepared speech,
   prepared text, public speech, rating, reading, recital, recitation,
   revilement, sales talk, salutatory, salutatory address, say,
   screed, set speech, speech, speechification, speeching, talk,
   talkathon, tirade, tongue-lashing, valediction, valedictory,
   valedictory address, vilification, vituperation