Webster's Revised Unabridged Dictionary · 1913

Trisyllabic

Trisyllabic , adjective

[Latin trisyllabus, Greek {not transcribed}; {not transcribed} (see Tri-) + {not transcribed} a syllable: compare French trissyllabique.]

Of or pertaining to a trisyllable; consisting of three syllables; as, “syllable” is a trisyllabic word.

Also: Trisyllabical