Source : Webster's Revised Unabridged Dictionary (1913)

Trisyllabic \Tris`yl*lab"ic\, Trisyllabical \Tris`yl*lab"ic*al\,
   a. [L. trisyllabus, Gr. ?; ? (see {Tri-}) + ? a syllable: cf.
   F. trissyllabique.]
   Of or pertaining to a trisyllable; consisting of three
   syllables; as, ``syllable'' is a trisyllabic word. --
   {Tris`yllab"ic*al*ly}, adv.