impostor
Concise Oxford English Dictionary © 2008 Oxford University Press:
impostor /ɪmˈpɒstə(r)/ (also imposter)
▶noun a person who assumes a false identity in order to deceive or defraud.
– origin C16: from Fr. imposteur, from late L. impostor, contr. of impositor, from L. imponere (see impose).
'impostor' also found in these Oxford entries:

