Hydrus noun. ['hʌɪdrǝs] In sense 1 hydrus; pl. -dri [-drʌɪ]. M17.
[Latin from Greek hudros water snake.]
1. A mythical water snake or sea serpent. rare. M17.

2. (The name of) a constellation of the southern hemisphere between the star Achernar and the pole; the Water Snake. Cf. HYDRA noun 2. E18.

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