hydra

[ hahy-druh ]
/ ˈhaɪ drə /

noun, plural hy·dras, hy·drae [hahy-dree] /ˈhaɪ dri/ for 1–3, genitive hy·drae [hahy-dree] /ˈhaɪ dri/ for 4.

(often initial capital letter) 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.
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.
a persistent or many-sided problem that presents new obstacles as soon as one aspect is solved.
(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

1325–75; < Latin < Greek hýdrā water serpent (replacing Middle English ydre < Middle French < L); see otter

Example sentences from the Web for hydra

British Dictionary definitions for hydra (1 of 3)

hydra
/ (ˈhaɪdrə) /

noun plural -dras or -drae (-driː)

any solitary freshwater hydroid coelenterate of the genus Hydra, in which the body is a slender polyp with tentacles around the mouth
a persistent trouble or evil the hydra of the Irish problem

Word Origin for hydra

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

British Dictionary definitions for hydra (2 of 3)

Hydra 1
/ (ˈhaɪdrə) /

noun

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)

Hydra 2
/ (ˈhaɪdrə) /

noun Latin genitive Hydrae (ˈhaɪdriː)

a very long faint constellation lying mainly in the S hemisphere and extending from near Virgo to Cancer

Scientific definitions for hydra

hydra
[ hīdrə ]

Plural hydras hydrae (drē)

See under hydroid.