"one of the indeclinable parts of speech, so called from being ordinarily joined to verbs for the purpose of limiting or extending their signification, but used also to qualify adjectives and other adverbs" [Century Dictionary], late 14c., from Late Latin adverbium "adverb," literally "that which is added to a verb" (to extend or limit its meaning), from ad "to" (see ad-) + verbum "verb, word" (from PIE root *were- (3) "to speak;" see verb). Coined by Flavius Sosipater Charisius as a translation of Greek epirrhema "adverb," from epi- "upon, on" + rhema "verb."
early 14c., rethorike, "the art of eloquence and persuasiveness in language, the art of using language to influence others," from Old French retorike, rethorique (Modern French rhétorique) and directly from Latin rhetorice, from Greek rhētorikētekhnē "art of an orator," from rhētōr (genitive rhētoros) "speaker, master speaker, orator; artist of discourse; teacher of rhetoric," especially (in the Attic official language), "orator in public." This is related to rhesis "speech," rhema "word, phrase, verb," literally "that which is spoken" (from PIE *wre-tor-, from root *were- (3) "to speak;" see verb). Since classical times with a derogatory suggestion of "artificial oratory" as opposed to what is natural or unaffected, "ostentatious declamation."