octogenarian
词根词缀：
octagon n. 八角形
octa 八 + gon 角 → 八角形
October n. 十月（古罗马八月）
octogenarian n. 80~89岁的老人
octo 八 + gen 出生 + arian 表人 → 出生以后活了八十多年的人 → 80~89岁的老人
octolateral adj. 八边的
octo 八 + later 边 + al …的 → 八边的
octopus n. 章鱼
octo 八 + pus 足 → 八爪鱼 → 章鱼
数据来源：新东方英语词汇速记大全
相关例句：
Kim Yong-nam, an octogenarian apparatchik who heads the parliament, delivered the funeral oration, saying the ideological heart of the nuclear-armed state would remain the armed forces.
年逾八旬的朝鲜最高人民会议常任委员会委员长金永南（Kim Yong-nam）致悼词，他表示，在这个拥有核武的国家，武装部队仍将置身于意识形态的中心。
William Chang Suk-ping was busy on a Beijing film set when he got a phone call from his octogenarian mother, who lives in Hong Kong.
当张叔平（William Chang Suk-ping）接到他年迈的母亲从香港打来的电话时，他正忙着为一部电影布景。
A man tries to find false teeth at the bottom of Cheng Ching Lake in Greater Kaohsiung on Oct.18 after an octogenarian accidentally threw them into the lake along with some guava seeds.
一位男子十月十八日尝试以双脚寻找一副掉在澄清湖底的假牙。该副假牙由一位吃芭乐的八旬老翁不慎丢进湖底。
Comparison of Radial Versus Femoral Approach for Percutaneous Coronary Intervention in Octogenarian
80岁以上老年患者经桡动脉和股动脉途径行经皮冠状动脉介入治疗的对比研究
She is very active for an octogenarian.
她已经是八旬老人了，还很精神。
A study on suitable energy of parenteral nutrition with for octogenarian patients with systemic inflammatory response syndrome
应用合理热能肠外营养治疗高龄病人全身炎症反应综合征