/ Dictionary / Index O octogenarian: Meaning and Definition of Find definitions for: oc•to•ge•nar•i•an Pronunciation: (ok"tu-ju-nâr'ē-un), [key] — adj. of the age of 80 years. between 80 and 90 years old. —n. a person who is between 80 and 90 years old. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: octogenarian (Thesaurus) octofoil octomerous 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