The Collaborative International Dictionary of English v.0.48:

Rhetoric \Rhet"o*ric\, n. [F. rh['e]torique, L. rhetorica, Gr.
   ???? (sc. ???), fr. ??? rhetorical, oratorical, fr. ???
   orator, rhetorician; perhaps akin to E. word; cf. ??? to
   say.]
   1. The art of composition; especially, elegant composition in
      prose.
      [1913 Webster]

   2. Oratory; the art of speaking with propriety, elegance, and
      force. --Locke.
      [1913 Webster]

   3. Hence, artificial eloquence; fine language or declamation
      without conviction or earnest feeling.
      [1913 Webster]

   4. Fig. : The power of persuasion or attraction; that which
      allures or charms.
      [1913 Webster]

            Sweet, silent rhetoric of persuading eyes. --Daniel.
      [1913 Webster]

WordNet (r) 3.0 (2006):

rhetoric
    n 1: using language effectively to please or persuade
    2: high-flown style; excessive use of verbal ornamentation; "the
       grandiosity of his prose"; "an excessive ornateness of
       language" [syn: grandiosity, magniloquence, ornateness,
       grandiloquence, rhetoric]
    3: loud and confused and empty talk; "mere rhetoric" [syn:
       palaver, hot air, empty words, empty talk,
       rhetoric]
    4: study of the technique and rules for using language
       effectively (especially in public speaking)

Moby Thesaurus II by Grady Ward, 1.0:

151 Moby Thesaurus words for "rhetoric":
   Barnumism, affectation, articulateness, bedizenment, big talk,
   bluster, bombast, choice of words, command of language,
   command of words, composition, convolution, debating, declamation,
   demagogism, dialect, diction, effective style, elocution,
   eloquence, eloquent tongue, exaggeration, expression,
   expression of ideas, expressiveness, facundity, fashion,
   feeling for words, felicitousness, felicity, flashiness,
   flatulence, flatulency, forensics, form of speech, formulation,
   fulsomeness, fustian, garishness, gasconade, gaudiness,
   gift of expression, gift of gab, glibness, grace of expression,
   grammar, grandiloquence, grandioseness, grandiosity, graphicness,
   high-flown diction, highfalutin, homiletics, hot air, idiom,
   inflatedness, inflation, language, lecturing, lexiphanicism,
   literary style, locution, loftiness, long-windedness, luridness,
   magniloquence, manner, manner of speaking, mannerism,
   meaningfulness, mere rhetoric, meretriciousness, mode,
   mode of expression, oratory, orotundity, ostentation,
   ostentatious complexity, parlance, peculiarity, personal style,
   phrase, phraseology, phrasing, platform oratory,
   platitudinous ponderosity, polysyllabic profundity, pomposity,
   pompous prolixity, pompousness, pontification, pretension,
   pretentiousness, prolixity, prose run mad, public speaking,
   puffery, pyrotechnics, rabble-rousing, rant, rhapsody,
   rhetoricalness, rodomontade, sensationalism, sense of language,
   sententiousness, sesquipedality, showiness, silver tongue,
   slickness, smoothness, speaking, speech, speechcraft,
   speechification, speeching, speechmaking, stiltedness, strain,
   stump speaking, style, stylistic analysis, stylistics,
   swelling utterance, swollen phrase, swollenness, talk, tall talk,
   the grand style, the plain style, the sublime, tortuosity,
   tortuousness, trick, tumidity, tumidness, turgescence, turgidity,
   usage, use of words, usus loquendi, vein, verbiage, verbosity,
   vividness, way, windiness, wordage, wordcraft, wordiness,
   wording