Are "Debar," "deprive," "prevent" synonyms?

Debarred is not a word anybody really uses, though it IS a word, I guess. Barred or banned would be much more common. And no, they are not synonyms. Debarred, barred or banned (which are synonyms) means that one is forbidden for some personal or legal reason. Lawyers can be "disbarred" which means they are no longer permitted to practice law, for whatever reasons. Deprived means lacking something, usually on purpose. Children are deprived of a normal childhood due to parental neglect, for instance. They aren't banned, they are lacking something because someone or something withheld it from them. Prevented is simpler and less profound. You are prevented from entering the building because the door is locked - unlock the door and you can enter. Or prevented from going into the White House because the guards wouldn't let you. You're not a bad person (you're not banned), it's just not possible.