pilaster
Definitions
A rectangular column, especially one projecting slightly from a wall.
An architectural element used to give the appearance of a supporting column, with only an ornamental function.
Examples
The architect added a decorative pilaster to the wall to give the room a more classical appearance.
The grand entrance was framed by two marble pilasters that supported the heavy stone archway.
Although it looks like a column, the pilaster is actually a rectangular feature attached directly to the building's facade.