Other forms: imposters
An imposter is somebody pretending to be who they are not. Expose the imposter, an imposter in uniform, feel like an imposter.
Both spellings are used and impostor with an o is the older and more formal one. Imposter syndrome is the common feeling that you do not deserve your position and will be found out, which is oddly commonest among people who plainly do deserve it.
1nounimposterSomebody pretending to be who they are not.
“The man in the doctor's coat turned out to be an imposter with no medical training.”
imposter is a deceiver.
Also accepted in games: impostor
From impostor, from Latin impostor, a deceiver, from imponere, to impose upon. The -er spelling grew up alongside.
Replacement of impostor -or with -er.
Etymology from Wiktionary, CC BY-SA