The Collaborative International Dictionary
Octosyllabical
Octosyllabic \Oc`to*syl*lab"ic\, Octosyllabical \Oc`to*syl*lab"ic*al\, a. [L. octosyllabus. See Octo-, and Syllable.] Consisting of or containing eight syllables.
Wiktionary
octosyllabical
a. (alternative form of octosyllabic English)