1. 不需要的;不必要的
    Something that is needless is completely unnecessary.

    e.g. But his death was so needless...
           但他的死太没有必要了。
    e.g. 'I have never knowingly exposed any patient to needless risks,' he said.
           他说：“我从未故意将任何病人置于不必要的风险境地。”

2. 不用说;不必说
    You use needless to say when you want to emphasize that what you are about to say is obvious and to be expected in the circumstances.

    e.g. Our budgie got out of its cage while our cat was in the room. Needless to say, the cat moved quicker than me and caught it.
           我们的虎皮鹦鹉飞出鸟笼的时候，猫正好在室内。不用说，猫比我快，抓住了它。