impostor

im·pos·tor

  [im-pos-ter]

–noun

a person who practices deception under an assumed character,identity, or name.

Also, im·post·er.

Origin: 
1580–90;  < Late Latin,  equivalent to Latin impos ( i )-, variantstem of impōnere  to deceive, place on ( see impone) + -tor -tor

treachery

treach·er·y

[trech-uh-ree]

–noun, plural -er·ies.

1.

violation of faith; betrayal of trust; treason.

2.

an act of perfidy, faithlessness, or treason.

disingenuous

dis·in·gen·u·ous

  [dis-in-jen-yoo-uhs]

–adjective

lacking in frankness, candor, or sincerity; falsely or hypocritically; insincere: Her excuse was rather disingenuous.