newel
One can fasten down a newel post using a screw driver. The screws can be used to fasten the newel post in place. Alternatively bolts can be used for this task.
A bannister post is called a ( Newel Post )
The ball on top of a stair post is commonly referred to as a "newel cap" or "newel ball." It is often decorative and serves to complete the look of the newel post, which is the upright post at the bottom or top of a staircase. Newel caps can come in various styles and materials, contributing to the overall aesthetic of the staircase.
a newel post
The newel post as a structural element in staircases dates back to ancient times, but its current form is credited to the Victorian era in the 19th century. While there isn't a single inventor of the newel post, it is commonly associated with the architectural styles of that period.
A 'Newel'
Try http://www.distinctivewooddesigns.com/newelposts.php
If you're referring a reference in my favorite Christmas movie, try a search for "newel post".
Newel also spelt newell
The post actually is the banister. The fat bit that you slide your hand on is called a handrail or a balustrade.
A newel is part of a staircase and is the vertical post at the foot of a staircase, at angles where the staircase changes direction or around which wind the steps of a circular staircase.