/ Dictionary / Index O octa-: Meaning and Definition of Find definitions for: octa- Pronunciation: [key] a combining form occurring in loanwords from Greek and Latin, where it meant “eight” (octagon; octastyle), on this model, used in the formation of compound words, and in chemical terms specialized to mean “having eight atoms” (octavalent). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. oct- octachord Related Content Daily Word Quiz: acquiesce Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language