Breastrail

A protective railing or bar positioned at chest height, commonly found on ships, balconies, or staircases to prevent people from falling.

Compound of 'breast' (Old English 'breost', the front of the body) and 'rail' (from Old French 'reille', a bar or rod). The term emerged in maritime contexts in the 16th-17th centuries to describe safety barriers positioned at torso level.