1 that does not work well, that does not achieve anything 无效的；无用的: This new machine is useless. 这台新机器没有用处。It's useless complaining/to complain -- you won't get your money back. 抱怨也无济于事，你的钱还是不能取回。

2 (informal 非正式)useless (at sth/at doing sth) (used about a person) weak or not successful at sth （指人）无能的，差劲的: I'm useless at sport. 我运动很差劲。 ➔uselessly adv ➔uselessness noun [U]