Ravelin (răvl&ibreve_;n; 277), n. [F.; cf. Sp. rebellin, It. revellino, rivellino; perhaps fr. L. re- again + vallum wall.] (Fort.) A detached work with two embankments which make a salient angle. It is raised before the curtain on the counterscarp of the place. Formerly called demilune and half-moon.
[1913 Webster]