'banns' originates from Old English/Old French, specifically the word 'bann' (Old French 'ban'), where the root meant 'a proclamation, public command'.

'banns' changed from Middle English/Old English word 'bann' (a proclamation) and through usage in ecclesiastical contexts became the specialized plural form 'banns' meaning the announcement of a forthcoming marriage.

Initially, it meant 'a proclamation or public command', but over time it evolved into the current specialized meaning of 'a public announcement of an intended marriage'.