A medialuna (literally half moon) is crescent-shaped corral used for rodeos, the official sport in Chile. They are generally 64–66 metres in diameter. Chilean rodeos are not quite the same sport famous in the American West; they involve two riders on horseback trying to herd a calf around a circular arena, attempting to pin him against several l...[genus] Medialuna is a genus of sea chubs native to the eastern Pacific Ocean. There are currently two recognized species in this genus: ...
• (n.) See Half-moon.
Me'di·a·lu'na noun [ Spanish media luna half-moon.] (Zoology) See Half- moon . 
medialuna 1. The moon at the quarters, when half its disk appears illuminated. 2. The shape of a half-moon; a crescent. 3. An outwork composed of two faces, forming a salient angle whose gorge resembles a half-moon; now called, a ravelin.