1 Greek Mythology a giant and hunter who was changed into a constellation at his death. 2 Astronomy a conspicuous constellation (the Hunter), said to represent a hunter holding a club and shield. It lies on the celestial equator and contains many bright stars, including Rigel, Betelgeuse, and a line of three that form Orion’s belt.
(as genitive Orionis
/ˌôrēˈōnis/) used with a preceding letter or numeral to designate a star in this constellation:the multiple star Theta Orionis