1An inconspicuous southern constellation (the Water Snake), between the star Achernar and the south celestial pole.

1. 1.1as genitive Hydri /ˈhʌɪdrʌɪ/ Used with preceding letter or numeral to designate a star in the Hydrus constellation.
   与其前面的字母或数字连用以标记该星座中的星水蛇星座的
   the star Delta Hydri

   水蛇座δ星。