Latin, Indo-European language of the Italic group, language of ancient Rome, and ancestor of the Romance languages. Originating in Latium (about 8th century B.C.), Latin spread with Roman conquests throughout the empire, differentiating into vulgar Latin and classical (literary) Latin. It is a logical and highly inflected language that has furnished scientific and legal terminology and is still used in the Roman Catholic Church. It was the international language of scholarship and diplomacy until the 18th century. About half of all English words are Latin in origin.