名詞 octogenarian:

1. someone whose age is in the eighties

形容詞 octogenarian:

1. being from 80 to 89 years old

1. She is very active for an octogenarian.
   她已經(jīng)是八旬老人了，還很精神。

oc.to.ge.nar.i.an

adj.（形容詞）
Being between 80 and 90 years of age.
在80到90歲之間的
n.（名詞）
A person between 80 and 90 years of age.
在80到90歲之間的人

來源：
From French octogénaire
源自 法語 octogénaire
from Latin octôgôn3rius [containing eighty]
源自 拉丁語 octôgôn3rius [含有八十的]
from octôgôno [eighty each]
源自 octôgôno [每一個八十]
from octôgint3 [eighty]
源自 octôgint3 [八十]
octô [eight] * see oktô(u)
octô [八] *參見 oktô(u)
-gint3 [ten times] * see dekô
-gint3 [十次] *參見 dekô