Hypocrisy is the act of pretending to have beliefs, virtues, ideas and feelings that the person actually does not. The word derives from Latin and Greek hypocrisis hupokrisis both meaning play a representation of an actor, acting, pretending (in the artistic sense). That word came later to appoint people who represent morally, pretending to conduct.
A classic example of a hypocritical act is to denounce another for carrying out some action whilst carrying out the same action.
Cognitive scientist Keith Stanovich has made a career of studying hypocrisy. He sees it as arising from the incompatibility of such things as self-interest and desires with higher order beliefs in morality and virtue. The only people who are not hypocrites are the tiny and perhaps non-existent minority who are so holy they never give to baser instincts and the largest group ever tries to live by principles of morality or virtue. He thus argues that the hypocrites are indeed the most noble class of people.
Francois duc de la Rochefoucauld revealed so scathing, the essence of hypocritical behavior, "hypocrisy is the tribute that vice pays to virtue." That is, every hypocrite pretends to emulate the correct behavior, virtuous, socially accepted.
The term hypocrisy is also commonly used (some would say misused) in a direction that could be designated more specifically as a "double standard". An example would be when one honestly believes that it should be a set of moral duty for a group of individuals different from another group.
Hypocrisy is pretense or pretending to be what's not. Hypocrite is a transcript from the Greek word "hypochrités. Greek actors wore masks according to the paper that represented a play. That's where the word hypocrite means someone who hides reality behind a mask of appearance.