Definition: To abjure was to renounce a heresy under oath. Christian heretics who wanted to reconcile with the Catholic Church made an abjuration, whereupon they would be given a penance and accepted back into the fold. Penance could be anything from wearing a cross sewn on all one's clothes for a set period of time to making a pilgrimage to the Holy Land.
However, should a heretic change his mind after abjuring, and either openly recant or return to espousing heresy, Church officials could (and usually did) hand him over to the secular authorities for punishment. The punishment for recanting an abjuration of heresy was usually execution, often by burning at the stake.
Examples:
Facing death, Joan of Arc signed a form of abjuration at the end of her trial; but she later maintained that St. Catherine and St. Margaret had admonished her for abjuring, and she recanted.
