What is Bans Of Matrimony?

Legal Definition
The giving public notice or making proclamation of a matrimonial contract, and the intended celebration of the marriage of the parties in pursuance of such contract, to the end that persons objecting to the same, may have an opportunity to declare such objections before the marriage is solemnized. Poth. Du Mariage, partie 2, c. 2. Vide Ban.
-- Bouviers Law Dictionary
Legal Definition
A public announcement of an intended marriage, required by the English law to he made in a church or chapel, duting service, on three consecutive Sundays before the marriage is celebrated. The object is to afford an opportunity for any person to interpose an objection lf he knows of any impediment or other just cause why the marriage should not take place. The publication of the bans may be dispensed wdth by procuring a special license to marry.
-- Black's Law Dictionary