'banister' ultimately originates from French and Italian sources, via French 'balustre' (from Italian 'balaustra'), where the root (from Greek 'balaustion') referred to a 'pomegranate flower'—a name given for the shape of early balusters.

'banister' developed as an English form related to 'baluster' (from French 'balustre' / Italian 'balaustra') and by alteration and use in early modern English the form 'banister' became established for the rail or its posts.

Initially the root referred to the 'pomegranate-flower' shape of a turned column (a baluster); over time the term shifted to refer to the supporting posts and then more broadly to the handrail assembly itself.