The thing is, canonesses had some similarities with nuns. Both groups lived in community under the authority of an abbess, devoting themselves to the religious life. Unlike nuns though, canonesses were not strictly enclosed and did not focus primarily on contemplation. They acted outside the cloister and were not bound to it, leaving to perform public liturgical functions like ringing the bells, taking part in synods* and participating in religious processions. They lived in individual quarters around the cloister, maintained personal property, and many employed their own servants. In many cases, it is hard to distinguish whether a particular group of women were canonesses or nuns. Many sources use the same term for both, in some cases as part of an effort to get canonesses to act more like nuns and restrict their movements.
Canonesses can be divided into two groups: regular and secular. Regular canonesses took permanent vows and lived strictly according to a Rule, usually that of St. Augustine. Secular canonesses, with the exception of the abbess, were not so bound and could leave to get married if they wished. Many communities of both sorts became centers of great learning, the best known being Quedlinburg and Gandersheim.
Male church officials were not so fond of the canonesses’ more free and less ascetic way of life and tried many times to restrict their movements, though there was only so much they could do. Most canonesses came from wealthy, powerful families with an interest in maintaining their female relatives’ freedom and the political power that came with it. They managed to defend their status up to the Reformation, at which point most communities of canonesses became Protestant and either disbanded or continued to exist as communities of single women.
Makowski, Elizabeth. "A Pernicious Sort of Woman": Quasi-Religious Women and Canon Lawyers in the Later Middle Ages. Catholic University of America Press, 2005.
McNamara, Jo Ann. Sisters in Arms: Catholic Nuns Through Two Millennia. Cambridge, MA: Harvard University Press, 1996.
Canoness - Catholic Encyclopedai
Canons and Canonesses Regular - Catholic Encyclopedia