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。