This word originates from the Greek hupokrites, meaning "an actor on the stage, a pretender, a dissembler". The two halves of the word have passed into modern English as hypo-, "under" or "below", and criticize. The complete Greek word was used in the sense of judging something as different than what it really was, as an actor pretending to be someone he wasn't.

Today, the word implies a person who "acts" his ethics, morals, or beliefs one way in front of others and a completely different way in private. It's never used as a compliment.