phony

Fraudulent; fake; having a misleading appearance.

A good jeweler should be able to tell a real stone from a phony one.

[…] one wonders whether the function of statistical techniques in the social sciences is not primarily to provide a machinery for producing phoney corroborations and thereby a semblance of ‘scientific progress’ where, in fact, there is nothing but an increase in pseudo-intellectual garbage.

A person who assumes an identity or quality other than their own.

He claims to be a doctor, but he's nothing but a fast-talking phony.

What a deal that was. You never saw so many phonies in all your life, everybody smoking their ears off and talking about the play so that everybody could hear and know how sharp they were.

A person who professes beliefs or opinions that they do not hold.

He's such a phony, he doesn't believe half of what he says.

Anything fraudulent or fake.

One name was a phony, but the other was the true name. The clerk remembered the man who had filed the tags since he acquired two sets of plates with different names.

To fake.