WordNet (r) 3.0 (2006):

logorrhea
    n 1: pathologically excessive (and often incoherent) talking
         [syn: logorrhea, logomania]

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "logorrhea":
   abundance, amplitude, cloud of words, copiousness, diffuseness,
   diffusion, diffusiveness, effusion, effusiveness, extravagance,
   exuberance, fecundity, fertility, flow of words, fluency,
   flux of words, formlessness, gush, gushing, logomania,
   long-windedness, longiloquence, macrology, outpour, overflow,
   palilogy, pleonasm, prodigality, productivity, profuseness,
   profusion, prolificacy, prolificity, prolixity, rampancy, rankness,
   redundancy, reiteration, reiterativeness, repetition for effect,
   repetitiveness, superabundance, superfluity, superflux,
   talkativeness, tautology, teemingness, tirade, verbal diarrhea,
   verbalism, verbality, verbiage, verbosity, wordiness