Noun:

1. someone whose age is in the nineties

Adjective:

1. being from 90 to 99 years old;

   "the nonagenarian inhabitants of the nursing home"
   

nonprosv.对(原告)作缺席判决nonadv.[拉]非；不是nonlocal pseudopotential非局域赝势non-recurring receipts临时收入,非经常性收入non-crystal oscillator无晶体振荡器non-commercial purpose非商业目的Non-polluted vegetable无公害蔬菜non-affiliated company非联系公司non-uniform excitation非一致激励non - standard English非标准英语nonconforming end office不一致端局non-related processing不相关过程

1. For a nonagenarian, he puts great faith in youthful optimism.
   就一个90多岁高龄的人而言，他有着一颗年轻乐观的心。