Learn how to say Impostor correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word impostor:
a person who pretends to be someone else in order to deceive others, especially for fraudulent gain:
the charity has warned anyone approached by the impostor to contact police immediately
late 16th century (in early use spelled imposture, and sometimes confused with imposture in meaning): from French imposteur, from late Latin impostor, contraction of impositor, from Latin imponere (see impose)