Wow, this is difficult! But I will try my best to help you. To negate is to make something negative or untrue. "This research negates the common assumption." It is frequently used in the context of facts and research. To contradict is to claim outright that something is untrue, sometimes (but not always) in a rude or unpleasant manner. Usually it is used in the context of people talking. "I contradicted my brother, because he said that the sky is green." To belie is to make something appear to be different than it is. "Her shy manner belied the fact that she was actually friendly and talkative with her close friends." To refute is to present evidence and logical arguments to prove that something is untrue. Often it is used in academic contexts. "In my paper, I refuted Professor Smith's claim that elephants are tiny." To rebut is like to refute, but it is less compete. Perhaps I have a wrong view of the word (contradict me if I'm wrong! :) ) but I think that when you rebut an argument, you simply argue against it. You do not definitively prove that it is false, which you do when you refute it. Rebut is often used in legal and political contexts. I hope that helped!