Hypocrisy is the state of pretending to have virtues, moral or religious beliefs, principles, etc., that one does not actually have. Hypocrisy involves the deception of others and is thus a kind of lie.
Hypocrisy is not simply failing to practice those virtues that one preaches. Samuel Johnson made this point when he wrote about the misuse of the charge of "hypocrisy" in Rambler No. 14:
"Nothing is more unjust, however common, than to charge with hypocrisy him that expresses zeal for those virtues which he neglects to practice; since he may be sincerely convinced of the advantages of conquering his passions, without having yet obtained the victory, as a man may be confident of the advantages of a voyage, or a journey, without having courage or industry to undertake it, and may honestly recommend to others, those attempts which he neglects himself."