Fake is an English word that can be used as a noun, verb, or adjective.
As an adjective: not genuine; counterfeit or imitation.
As a noun: a thing that is not genuine; a forgery or sham.
As a verb: to make (something) seem real or true in order to deceive someone.
In internet slang, "fake" often refers to:
1. Fake news - false information spread as news
2. Fake accounts - social media accounts created under false identities
3. Fake it till you make it - a self-help strategy