Bāstion, n.

(bāst'yun), n. [Fr. & Sp. bastion, Pr. bastio, It. bastione, from O. Fr., Pr., & Sp. bastir, It. bastire, to build.] (Fort.) A part of the main inclosure which projects toward the exterior, consisting of the faces and the flanks. Two adjacent bastions are connected by the curtain, which joins the flank of one with the adjacent flank of the other. The distance between the flanks of a bastion is called the gorge. A lunette is a detached bastion. [See also Illust. of Ravelin.]

A, bastion, Barcelona; a, curtain angle; b, shoulder angle; c, salient angle; a, a, gorge; a, b, flank; a, d, curtain; b, c, face.