Definition of hydra noun from the Oxford Advanced Learner's Dictionary



    BrE BrE//ˈhaɪdrə//
    ; NAmE NAmE//ˈhaɪdrə//
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  1. 1 Hydra (in ancient Greek stories) a snake with several heads. As one head was cut off, another one grew. In the end it was killed by Hercules.
  2. 2(formal) a thing that is very difficult to deal with, because it continues for a long time or because it has many different aspects
  3. 3(biology) an extremely small water creature with a tube-shaped body and tentacles around its mouth
  4. Word Originvia Latin from Greek hudra ‘water snake’, named by Linnaeus because, if cut into pieces, each section can grow into a whole animal.
See the Oxford Advanced American Dictionary entry: hydra