Gooseneck: The curved upper end of a stair rail.

Newel: The post that supports the handrail at the bottom of a staircase; the central vertical support of a spiral staircase.

Nosing: A rounded convex edge, as on a stair step.

Riser: The vertical surface of a stair step.

Spandrel: The triangular element in a staircase between the stringer and the baseboard.

Spline: A thin strip forming a key between two boards, fitting into slots along their edges and locking them together.

Split baluster: A baluster cut lengthwise and applied to a flat surface as an ornament.

Stringer: A diagonal element supporting the treads and risers in a flight of stairs.

Tread: The horizontal surface of a stair step.

Volute: The spiral decorative element terminating the lower end of a stair rail.