I. in the Roman Church, a formal and solemn act by which heretics and those suspected of heresy denied and renounced it. In countries where the inquisition was established, three sorts of abjuration were practiced:
1. Abjuratio deformali, made by a notorious apostate or heretic;
2. Abjuratio de vehementi, made by a Roman Catholic strongly suspected of heresy;
3. Abjuratio de levi, made by a Roman Catholic only slightly suspected.
II. In England, the oath of abjuration is an oath by which an obligation was come under not to acknowledge any right in the Pretender to the throne of England. It is also used to signify an oath ordained by the 25th of Charles II, abjuring particular doctrines of the Church of Rome. (See S. G. Wald, De Haeresi Abjuranda, Regiom. 1821; Vond. Abschworrung der Simonie, in Henke's Eusebia, 1:184 sq.) SEE HERETIC.