A minute freshwater coelenterate with a tubular body and a ring of tentacles around the mouth.
Genus Hydra, class Hydrozoa
- ‘The Phylum Cnidaria includes such diverse forms as jellyfish, hydra, sea anemones, and corals.’
- ‘The same is true for hydra, a freshwater cnidarian.’
- ‘There are some animals that don't belong to the Bilateria, though: members of the phylum Cnidaria, the jellyfish, hydra, sea anemones, and corals, which are typically radially symmetric.’
- ‘Several drawings depict forms that have the amorphous shapes of sea life such as hydras and jellyfish.’
- ‘Roughly like a giant squid, or one of those micoscopic hydras, but blown up to immense proportions.’
Via Latin from Greek hudra ‘water snake’ (see Hydra), named by Linnaeus because, if cut into pieces, each section can grow into a whole animal.
A many-headed snake whose heads grew again as they were cut off, eventually killed by Hercules.
- 1.1as noun a hydraA thing that is hard to overcome or resist because of its pervasive or enduring quality or its many aspects.‘his battle with the hydra of bureaucracy’
- ‘Database scalability is a many-headed hydra that's hard to define, let alone tame.’
- ‘Yet it appears that multi-headed hydra, our scientific research establishment, is pulling in more than 200 different directions.’
- ‘There were very few studies on this multi-headed hydra so far.’
- ‘And the wife in this two-headed hydra of nonsense claims to have a degree in biology.’
- 1.1as noun a hydraA thing that is hard to overcome or resist because of its pervasive or enduring quality or its many aspects.
The largest constellation (the Water Snake or Sea Monster), said to represent the beast slain by Hercules. Its few bright stars are close to the celestial equator.
- 2.1as genitive Hydrae /ˈhʌɪdriː/Used with preceding letter or numeral to designate a star in the Hydra constellation.‘the star Beta Hydrae’
- 2.1as genitive Hydrae /ˈhʌɪdriː/Used with preceding letter or numeral to designate a star in the Hydra constellation.
Via Latin from Greek hudra.