noun
banister
BAN-uh-ster/ˈbænɪstər/
A handrail with supporting posts along stairs.
The wooden banister runs along the staircase, supported by upright posts.

Etymology
Balaustro meant a small pillar, the upright support beneath a railing. It is said to take its name from the pomegranate flower, whose half-open shape resembled the curved supports; banister also names the railing assembly.
In context
my feet gave way beneath me and I had to support myself against the iron banister
More examples
- The carpenter repaired a loose section of the banister.
- Polished banisters ran along both sides of the staircase.
- A child slid one hand along the banister while descending.
Forms
banister · banisters
Similar words
- handrail
- Names the rail itself rather than the whole supported structure.
- balustrade
- Is a more formal term for a railing with supporting posts.