Emily Dickinson Lexicon

PI-LAS'TER, n. [It. pilastro; Fr. pilastre; Sp. pilastra, from pila, a pile, whence pillar.]

A square column, sometimes insulated; but usually pilasters are set within a wall, projecting only one quarter of their diameter. Their bases, capitals and entablatures have the same parts as those of columns. – Encyc.