hydrus

from WordNet (r) 3.0 (2006)

Hydrus
    n 1: a constellation in the southern hemisphere near the south
         celestial pole

from The Collaborative International Dictionary of English v.0.48

Hydrus \Hy"drus\, n. [L., a water serpent; also, a certain
   constellation, Gr. "y`dros.] (Astron.)
   A constellation of the southern hemisphere, near the south
   pole.
   [1913 Webster]