noun a person who professes beliefs and opinions that he or she does not hold in order to conceal his or her real feelings or motives.
— synonyms: hypocrite, dissembler, dissimulator, phoney, pretender
Examples
“He claims to be a doctor, but he's nothing but a fast-talking phony.”
“He's such a phony, he doesn't believe half of what he says.”
“A good jeweler should be able to tell a real stone from a phony one.”