名詞 nonagenarian:

1. someone whose age is in the nineties

形容詞 nonagenarian:

1. being from 90 to 99 years old

non.a.ge.nar.i.an

n.（名詞）
A person 90 years old or between 90 and 00 years old.
九十至九十九歲的人：90歲或處于90歲到00歲之間的人

來源：
From Latin nôn3gôn3rius
源自 拉丁語 nôn3gôn3rius
from nôn3gôno [ninety each]
源自 nôn3gôno [九十個每個]
from nôn3gint3 [ninety]
源自 nôn3gint3 [九十]
nônus [ninth] * see nona-
nônus [第九] *參見 nona-
-gint3 [ten times] * see dekô
-gint3 [十倍] *參見 dekô

【引伸】
non.agenar.ian
adj.（形容詞）