1. (n.) The moon at the quarters, when half its disk appears illuminated.
2. (n.) The shape of a half-moon; a crescent.
3. (n.) An outwork composed of two faces, forming a salient angle whose gorge resembles a half-moon; -- now called a ravelin.
4. (n.) A marine, sparoid, food fish of California (Caesiosoma Californiense). The body is ovate, blackish above, blue or gray below. Called also medialuna.