Crux (krŏŏks) [Lat.,=cross], small but brilliant southern constellation whose four most prominent members form a Latin cross, the famous Southern Cross. The long arm of the cross, terminating in the brightest member, Acrux (Alpha Crucis), points almost directly at the south celestial pole. Two other stars, Mimosa (Beta Crucis) and Gacrux (Gamma Crucis) are also among the brightest in the sky. Also in Crux is the Coalsack, a famous dark nebula. Crux reaches its highest point in the evening sky in May; its location in the far southern sky makes it visible most of the year to southern observers but not at all to observers north of about 25°N lat.
crux / krəks; kroŏks/ • n. (pl. crux·es or cru·ces / ˈkroōˌsēz/ ) (the crux) the decisive or most important point at issue: the crux of the matter is that attitudes have changed. ∎ a particular point of difficulty.
Crux / krəks; kroŏks/ Astron. another term for the Southern Cross. ∎ [as genitive] (Cru·cis / ˈkroōsis/ ) used with a preceding letter or numeral to designate a star in this constellation: the star Beta Crucis.