/ Dictionary / Index N nonagenarian: Meaning and Definition of Find definitions for: non•a•ge•nar•i•an Pronunciation: (non"u-ju-nâr'ē-un, nō"nu-), [key] — adj. of the age of 90 years, or between 90 and 100 years old. —n. a nonagenarian person. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: nonagenarian (Thesaurus) nonage nonaggression Related Content Daily Word Quiz: clairvoyant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language