(of people) to say the opposite of what someone else has said, or (of one fact or statement) to be so different from another fact or statement that one of them must be wrong

If you're both going to lie, at least stick to the same story and don't contradict each other! 如果你们俩都要撒谎，至少也要口径一致，不要互相矛盾！

He kept contradicting himself when we were arguing - I think he was a bit confused. 我们争论时他一直自相矛盾——我想他有点糊涂了。

How dare you contradict (me)! 你怎么敢顶撞我！

Recent evidence has contradicted established theories on this subject. 关于这一问题，最近发现的证据与已有理论相抵触。