octogenarian

详细解释:a. 80岁到90岁(的人)的
n. 80岁到90岁的人

英语解释：

名词 octogenarian:

someone whose age is in the eighties

形容词 octogenarian:

being from 80 to 89 years old

例句：

She is very active for an octogenarian.她已经是八旬老人了，还很精神。