Cap
The upper member of a column, pilaster, door cornice, molding, and the like.

Capital
The elaboration at the top of a column, pillar, pier or pilaster.

Column
A vertical component of a structure, usually supporting part of the structure. May also be purely decorative

Corinthian
The type of Greek column characterized by simulated acanthus leaves.

Ionic
The type of Greek column characterized by scroll-like decorations.

Lally Column
A steel tube sometimes filled with concrete, used to support girders or other floor beams.

Modillion
A bracket supporting the upper part of a composite or Corinthian cornice

Pier
A vertical, non-circular masonry support, more massive than a column.

Pilaster
A flat, shallow rectangular column projecting from a wall with a base and.

Pillar
Similar to but more slender than a pier, also non-circular.

Shaft
A long, slender part of a pillar that adds support to an overhanging structure.