/ Dictionary / Index O octocentenary: Meaning and Definition of Find definitions for: oc•to•cen•ten•ar•y Pronunciation: (ok"tō-sen-ten'u-rē, -sen'tn-er"ē or, esp. Brit., -sen-tē'nu-rē), [key] — adj., n., pl. -ar•ies. —adj. pertaining to 800 or a period of 800 years; marking the completion of 800 years. —n. an 800th anniversary or its celebration. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Octobrist octodecillion 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