ill名词形式为illness，ill可以做副词也可以做形容词，意思为“疾病； 某种具体疾病； 不健康”。

Attitudes to mental illness have shifted in recent years.最近几年对精神病的态度已有所改变。He boasts of dodging military service by feigning illness.他炫耀自己通过装病来逃避服兵役。She was determined not to let the illness take hold again.她决心不让疾病再次击垮自己。