(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.