the title of a superior of certain communities of nuns following the Benedictine Rule, of convents of the Second Order of St. Francis (Poor Clares), and of certain communities of canonesses. The first historical record of the name is on a Roman inscription dated c. 514.

To be elected, an abbess must be at least 40 years old and a professed nun for at least 10 years. She is solemnly blessed by the diocesan bishop in a rite similar to that of the blessing of abbots. Her blessing gives her the right to certain pontifical insignia: the ring and sometimes the crosier.

In medieval times abbesses occasionally ruled double monasteries of monks and nuns and enjoyed various privileges and honours. See also abbot.