Monoceros () is a constellation on the celestial equator. Its name is Greek for unicorn. It was described by 17th-century Dutch cartographer Petrus Plancius. Orion is to the west of Monceros. Gemini is to the north. Canis Major is to the south. Hydra is to the east. Other constellations next to Monoceros are Canis Minor, Lepus and Puppis.