E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Ravelin (The) or demi-lune,
in fortification. A work with two faces, forming a salient angle, placed beyond the main ditch, opposite the curtain (q.v.), and separated from the covered way (q.v.) by a ditch which runs into the main ditch.
