'Hydrus' definitions:

Definition of 'Hydrus'

(from WordNet)
noun
A constellation in the southern hemisphere near the south celestial pole

Definition of 'Hydrus'

From: GCIDE
  • 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]