ill名词形式为illness.

illness：n.(身体或精神上的)疾病，病;(某种)病;患病期.

相关介绍

You may find your illness hard to accept.

你可能觉得难以接受自己患病。

The term 'mental illness' is difficult to define.

“精神病”这个词很难下定义。

The illness can be treated provided it's caught early enough.

此病若及早发现是可医治的。