Impostor

An impostor (also spelled imposter) is a person who pretends to be somebody else, often through means of disguise, often to try to gain financial or social advantages through social engineering, but just as often for purposes of espionage or law enforcement.

Many women in history have presented themselves as men in order to advance in typically male-dominated fields. In most cases their exact relationship to their male presentation was never recorded unambiguously or at all; if or how they would fit into modern Western transgender categories can never be certain.

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Wikipedia