Plural of banister; a series of upright posts (balusters) connected by a rail, typically running alongside stairs to provide safety and support.
From the singular 'banister,' which is a shortened form of 'baluster,' itself deriving from Italian 'balaustro' and ultimately Greek 'balaustion' meaning pomegranate flower, because the balusters resembled the shape of pomegranate buds.
Try Another Word