'banner' originates from Old French, specifically the word 'baniere' (also spelled 'banier' or 'banniere'), which referred to a flag or standard used as a sign or emblem.

'banner' entered Middle English from Old French 'baniere'; Old French itself comes from Late Latin 'bandum'/'bandum' (related to a sign or standard), and likely from a Germanic source (cf. Frankish *bandwa meaning 'sign, flag'), eventually becoming English 'banner'.

Initially it meant 'a flag, standard, or sign,' and over time it kept that core sense while also developing verbal uses meaning 'to mark or display with a banner' and adjectival uses meaning 'having a banner'.