pretense, pretension, pretensiousness

pretense

a false show

Example: I decided to keep up the pretense of friendship with her.

pretension

the laying of claim to something

Example: His pretension to proficiency in Electronics was shown to be false.

pretensiousness

characterized by assumption of dignity or importance

I can't stand the pretensiousness of people who go on a short visit to the US or UK and then start speaking with a fake accent.