Medical Dictionary

hydra

noun hy·dra \ˈhī-drə\

Medical Definition of HYDRA

:  any of numerous small tubular freshwater hydrozoan polyps (Hydra and related genera) having at one end a mouth surrounded by tentacles

Browse

How to use a word that (literally) drives some people nuts.
Test your vocab with our fun, fast game
Ailurophobia, and 9 other unusual fears