Banns

The banns of marriage or, simply "the banns", (from an Old English word meaning "to summon") are the public announcement from the pulpit that a marriage is going to take place in that church between two specified persons at a specified time. Their purpose is to allow anyone to come to the wedding to raise any legal impediment to it—such an impediment might be a prior marriage (or pre-contract or betrothal, those being legally the same as a marriage), or a vow of celibacy, or the couple's being related within the prohibited degree of kinship, or lack of consent—to prevent marriages that are legally invalid, either under canon law or under civil law. http://en.wikipedia.org/wiki/Bann