A pilaster is a flat, column-shaped strip that is built as part of a wall, not standing free in the room. It looks like a square or rectangular pillar stuck onto the wall — with a base, a shaft, and often a top like a real column — but it is there mainly for show, to make the wall look grand or to break up a long surface. You see them on old public buildings, churches, and fancy houses. It is not holding the roof up in the way a true column might; though actually, some pilasters do a little structural work, but the point of the word is the attached, decorative column, not a round pillar you can walk around. Architects and art-history writing use it; everyday speakers just say column if they notice it at all.

壁柱、扁柱（貼在牆上做裝飾的方柱，不是可以繞行的獨立圓柱）。