Vertical Spindle in Railings Next to Stairs
Puzzle 9 of Building a House Hard Pack
Question is: Vertical Spindle in Railings Next to Stairs
and the answer is: BALUSTER
Word Meaning:
BALUSTER — (architecture) A short column used in a group to support a rail, as commonly found on the side of a stairway or around a balcony.
Definitions from Wiktionary.