An encyclical was originally a circular letter sent to all the churches of a particular area in the ancient Roman Church. At that time, the word could be used for a letter sent out by any bishop. The word comes from the Late Latin encyclios (originally from the Latin encyclius, a Latinization of Greek ἐνκύκλιος (enkyklios), meaning "circular", "in a circle", or "all-round", also part of the origin of the word encyclopedia).[1] The term has been used by Catholics, Anglicans and the Eastern Orthodox Church. Catholic social teaching has advanced 19 encyclicals.