What is a detached work with two embankments with make a salient angle. It is raised before the curtain on the counterscarp of the place. Formerly called demilune and half-moon called?

ravelin — A detached work with two embankments with make a salient angle. It is raised before the curtain on the counterscarp of the place. Formerly called demilune and half-moon. (Webster's 1913.)