Source : Webster's Revised Unabridged Dictionary (1913)

Polysyllabic \Pol`y*syl*lab"ic\, Polysyllabical
\Pol`y*syl*lab"ic*al\, a. [Gr. ?; poly`s many + ? syllable: cf.
   F. polysyllabique.]
   Pertaining to a polysyllable; containing, or characterized
   by, polysyllables; consisting of more than three syllables.

Source : WordNet®

polysyllabic
     adj 1: having or characterized by words of more than three
            syllables
     2: (of words) long and ponderous; having many syllables;
        "sesquipedalian technical terms" [syn: {sesquipedalian}]