nonagenarian

From Latin nōnāgēnārius (“containing ninety”) + -an (“forming adjectives and representative nouns”), either directly or via French nonagénaire, from nōnāgēnī (“ninety each”) + -ārius (“-ary”), from nōnāginta (“nine tens, ninety”).

• (General American) IPA^(key): /ˈˌnɑnəd͡ʒɪˈnɛriən/, /ˈˌnoʊnəd͡ʒɪˈnɛriən/
• (Received Pronunciation) IPA^(key): /ˌnɒnəd͡ʒɪˈnɛːrɪən/, /ˌnəʊnəd͡ʒɪˈnɛːrɪən/

nonagenarian (plural nonagenarians)

1. Synonym of ninetysomething: a person between 90 and 99 years old.

nonagenarian (not comparable)

1. Of or related to ninetysomethings.

   Coordinate terms: vicenarian, tricenarian, quadragenarian, quinquagenarian, semicentenarian, hexagenarian, sexagenarian, septuagenarian, octogenarian, centenarian, semisupercentenarian, supercentenarian

   • 1954, Alben W. Barkley, editor, That Reminds Me‎, Garden City, NY: Doubleday & Company, →LCCN, →OCLC, →OL, page 17:

     "But what’s that got to do with your health and longevity?" the neighbor inquired.
     "Why," said the nonagenarian, "I've spent most of my life in the open air."

• “nonagenarian, n. and adj.”, in OED Online ⁠, Oxford, Oxfordshire: Oxford University Press, 2022.