senile

/ˈsiːnaɪl/ 14GREsat
If old people become senile, they become confused, can no longer remember things, and are unable to take care of themselves. 衰老的; 年老糊涂的

adjective [原级]高龄的;老衰的;高龄所致的

I think she's going senile.
我想她是衰老了。

sen (老的) + ile (…的) → 老的 → 高龄的
单词造句:
网友用“Senile”造句精选
It tottered on the borders of senile decay. 它在衰老的边缘摇摇欲坠。
She is suffering from senile dementia. 她受老年痴呆症折磨。
The old man was forced to resign after showing unmistakable signs of senility. 那个老头明显有了年老糊涂的迹象后就被迫辞职了。