Emily Dickinson Lexicon

BAS'TION, n. [bas'chun; Fr. and Sp. bastion; It. bastione; probably from bastir, bâtir, to build, to set or found.]

A huge mass of earth, usually faced with sods, sometimes with brick, or stones, standing out from a rampart, of which it is a principal part; formerly called a bulwark. Bastions are solid or hollow. A flat bastion is made in the middle of the curtain, when it is too long to be defended by the bastions in its extremes. A cut bastion has its point cut off, and instead of it, a reentering angle, or an angle inward, with two points outward. A composed bastion has two sides of the interior polygon unequal, which makes the gorges unequal. A demibastion is composed of one face only, with one flank and a demigorge. A double bastion is one raised on the plane of another. – Encyc.