A vertical post, usually metal or wooden, that is used together with other such posts to form a fence. (Cambridge Dictionary)
The row of posts at the side of stairs and the wooden or metal bar on top of them. (Cambridge Dictionary)
A barrier consisting of a rail and supports. (Merriam – Webster)
A fence or barrier made of rails. (Oxford Dictionaries)
A fence made from metal bars is called a railing or railings. (Collins Dictionary)
Railings. Fence city.
Railings – Northern Ireland.