Baluster n. : A small column or pilaster, used as a support to the rail of an open parapet, to guard the side of a staircase, or the front of a gallery. See Balustrade.

Example:
Where can I purchase Baluster mold or concrete Baluster in the US?

Taxonomy
baluster, balustrades, shaft, wood baluster, Baluster Spacing, lathe, banister, architecture, free encyclopedia, open flower, stone balusters, palaces, legs, vase shape, stone, Michelangelo, balaustra, pomegranate.

Defination from the web:
baluster being a turned structure tends to follow design precedents that were set in woodworking and ceramic practices, where the turner's ... Some complicated Mannerist baluster forms can be read as a vase set upon another vase. ...