newel

A vertical support at the center of a circular staircase.

A post that supports a handrail at the bottom or at the landing of a staircase.

A new thing; a novelty.

In architecture, an upright cylinder or pillar which forms a center from which the steps of a winding stair radiate, and supports their inner ends from the bottom to the top.

In carpentry, the tall and more or less ornamental post at the head or foot of a stair, supporting a handrail.