When a celebrity wakes up in Las Vegas with a mysterious wedding ring on her finger, the first thing she’ll probably want to do is annul the marriage. That will declare it invalid and officially cancel the whole deal. Annul, which means “to cancel” or “to invalidate,” is usually used in the context of politics or marriage. New government officials often want to annul laws and policies of the previous post-holder, effectively reversing their work. When you annul a marriage, you are officially declaring it invalid, as if it never happened.