pilaster, in architecture, upright supporting member, attached to and projecting slightly from the face of a wall and equipped with a base and capital like a column; also, a similar form used decoratively. The pilaster in general follows the rules and proportions of the classic orders; it may be fluted or not, but usually has no entasis or taper. It was used by the Romans. The Greek antae (projections of the wall at the corners only), although similar in function, differ in base and capital from the columns that stand between them. In the Renaissance, the pilaster, used as a purely decorative device, was often paneled and ornamented.

In Classical architecture, a shallow rectangular column built into a wall and projecting slightly beyond it. It has a capital and base and conforms to one of the orders. In Roman architecture the pilaster gradually became more decorative than structural, and it served to break up otherwise empty expanses of wall.

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