An imposter is a person who pretends to be someone else. Someone who tries to convince you that he's your long lost cousin in order to get an invitation to stay in your awesome apartment is an imposter . What is the difference Imposter and Impostor ? Discover Imposter and Impostor definitions, examples, insights, and quiz Impostor definition : a person who practices deception under an assumed character, identity, or name.. See examples of IMPOSTOR used in a sentence. IMPOSTOR meaning : 1. a person who pretends to be someone else in order to deceive others: 2. a person who pretends…. Learn more.