/ Dictionary / Index O octo-: Meaning and Definition of Find definitions for: octo- Pronunciation: [key] var. ofoctosyllabic. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. octillion October Related Content Daily Word Quiz: fabricate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language