newel

kaidepylväs

keskuspylväs, keskipilari puhekieltä A central pillar around which a staircase spirals.
puhekieltä A sturdy pillar at the top or bottom of a flight of stairs, supporting the handrail.
1943, (w), The High Window, Penguin 2005, p. 238:

We went along the hall to the end and up a flight of stairs with a carved handrail and newel post.

He was so enamoured with the newel.