pilaster definition by Webster's New World
Origin: French pilastre ; from Italian pilastro ; from Classical Latin pila, a pile, column
pilaster definition by American Heritage Dictionary
Origin: French pilastre, from Old French, from Old Italian pilastro, from Medieval Latin pīlaster : Latin pīla, pillar + Latin -aster, n. suff., or blend of Latin pīla, pillar, and Late Latin parastatēs, pilaster (from Greek, stay, supporter : para-, beside; see para-1 + -statēs, -stat).