[ hahy-druh ]
See synonyms for hydra on Thesaurus.com
noun,plural hy·dras, hy·drae [hahy-dree] /ˈhaɪ dri/ for 1-3.
  1. Often Hydra .Classical Mythology. a water or marsh serpent with nine heads, each of which, if cut off, grew back as two; Hercules killed this serpent by cauterizing the necks as he cut off the heads.

  2. any freshwater polyp of the genus Hydra and related genera, having a cylindrical body with a ring of tentacles surrounding the mouth, and usually living attached to rocks, plants, etc., but also capable of detaching and floating in the water.

  1. a persistent or many-sided problem that presents new obstacles as soon as one aspect is solved.

  2. genitive Hy·drae [hahy-dree]. /ˈhaɪ dri/. (initial capital letter)Astronomy. the Sea Serpent, a large southern constellation extending through 90° of the sky, being the longest of all constellations.

Origin of hydra

First recorded in 1325–75; from Latin hydra, from Greek hýdrā “water serpent” (replacing Middle English ydre, from Middle French, from Latin); see otter

Words Nearby hydra

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How to use hydra in a sentence

British Dictionary definitions for hydra (1 of 3)


/ (ˈhaɪdrə) /

nounplural -dras or -drae (-driː)
  1. any solitary freshwater hydroid coelenterate of the genus Hydra, in which the body is a slender polyp with tentacles around the mouth

  2. a persistent trouble or evil: the hydra of the Irish problem

Origin of hydra

C16: from Latin, from Greek hudra water serpent; compare otter

British Dictionary definitions for Hydra (2 of 3)


/ (ˈhaɪdrə) /

  1. Greek myth a monster with nine heads, each of which, when struck off, was replaced by two new ones

British Dictionary definitions for Hydra (3 of 3)


/ (ˈhaɪdrə) /

nounLatin genitive Hydrae (ˈhaɪdriː)
  1. a very long faint constellation lying mainly in the S hemisphere and extending from near Virgo to Cancer

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for hydra


[ drə ]

Plural hydras hydrae (drē)

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.