Pillar, column, pilaster denote a structure that rises high from a base or foundation, is slender in comparison with its width, and usually has a monolithic and decorative appearance.
Pillar is the general term and applies to any such structure whether it stands alone or is a supporting architectural member of a building or similar structure.
In extended use pillar usually applies to something which stays or supports, but when the application is to persons the term usually suggests the character of one who supports, though it may also imply leadership or prominence.
Column in architectural use primarily applies to a supporting pillar that is often cylindrical and free at every point except its bottom and top. The term commonly also implies three more or less elaborate parts, the base, by which it is attached to the floor, the shaft, often a fluted or channeled cylinder which rises high from the base, and the capital, the uppermost member which crowns the shaft and takes the weight or its share of the weight of what rests on it.
But column is also applicable to a monument or memorial fashioned in the manner of an architectural column. By extension the term is also applicable to something that suggests a column especially in shape or in use or structure. Sometimes the suggestion is remote and the term is applied to anything that is long and relatively narrow.
Pilaster, though used with reference to a supporting member of a piece of furniture, is chiefly employed with reference to an architectural member which in function is a pier (see pier under BUTTRESS ) but which in design and treatment resembles a column. In this latter sense pilaster implies engagement or attachment to a wall and suggests a rectangular rather than cylindrical form.