'Polysyllable' definitions:

Definition of 'polysyllable'

From: WordNet
noun
A word of more than three syllables [syn: polysyllable, polysyllabic word]

Definition of 'Polysyllable'

From: GCIDE
  • Polysyllable \Pol"y*syl`la*ble\, n. [Poly- + syllable.] A word of many syllables, or consisting of more syllables than three; -- words of less than four syllables being called monosyllables, dissyllables, and trisyllables. [1913 Webster]