hydra

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Hy·dra

(hī′drə)

1. Greek Mythology The many-headed monster that was slain by Hercules.

2. Astronomy A satellite of Pluto.

3. A constellation in the equatorial region of the southern sky near Cancer, Libra, and Centaurus. Also called Snake².

4. A persistent or multifaceted problem that cannot be eradicated by a single effort.

[Middle English Idra, from Latin Hydra, from Greek Hudrā, Hydra, a water serpent; see wed- in Indo-European roots.]

hy·dra

(hī′drə)

n. pl. hy·dras or hy·drae (-drē)

Any of several small solitary freshwater hydrozoans of the genus Hydra and related genera, having a cylindrical body and a mouth surrounded by tentacles.

[New Latin Hydra, genus name, from Latin Hydra, Hydra; see Hydra.]

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

hydra

(ˈhaɪdrə)

n, pl -dras or -drae (-driː)

1. (Animals) 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.

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

Hydra

(ˈhaɪdrə)

(Classical Myth & Legend) Greek myth a monster with nine heads, each of which, when struck off, was replaced by two new ones

Hydra

(ˈhaɪdrə)

n, Latin genitive Hydrae (ˈhaɪdriː)

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

Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

hy•dra

(ˈhaɪ drə)

n., pl. -dras, -drae (-dri) for 1–3, gen. -drae (-dri) for 4.

1. (often cap.) a water monster of Greek myth having nine heads, each of which, if cut off, grew back as two.

2. any freshwater polyp of the family Hydridae, having a cylindrical body with a ring of tentacles surrounding the mouth.

3. a persistent or complex problem that presents new obstacles even as existing ones are overcome.

4. (cap.) the Sea Serpent, a southern constellation extending through 90° of the sky.

[1325–75; Middle English ydre < Middle French < Latin < Greek hýdrā water serpent; compare otter]

hy·dra

(hī′drə)

Any of several small freshwater polyps having a simple cylindrical body with a mouth-like opening surrounded by tentacles. The young develop from eggs or from buds.

The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

ThesaurusAntonymsRelated WordsSynonymsLegend:

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Noun	1.	Hydra - (Greek mythology) monster with nine heads; when struck off each head was replaced by two new ones; "Hydra was slain by Hercules" Greek mythology - the mythology of the ancient Greeks mythical creature, mythical monster - a monster renowned in folklore and myth
	2.	Hydra - a long faint constellation in the southern hemisphere near the equator stretching between Virgo and Cancer Snake
	3.	hydra - trouble that cannot be overcome by a single effort because of its many aspects or its persistent and pervasive quality; "we may be facing a hydra that defies any easy solution" trouble, problem - a source of difficulty; "one trouble after another delayed the job"; "what's the problem?"
	4.	hydra - small tubular solitary freshwater hydrozoan polyp hydroid, hydrozoan - colonial coelenterates having the polyp phase dominant genus Hydra - hydras

Translations

Wasserschlange

Ύδρα

Hydrahydre

idra

гидра

hydra

[ˈhaɪdrə] N (hydras or hydrae (pl)) [ˈhaɪdriː] → hidra f
Hydra (Myth) → Hidra f

Collins Spanish Dictionary - Complete and Unabridged 8th Edition 2005 © William Collins Sons & Co. Ltd. 1971, 1988 © HarperCollins Publishers 1992, 1993, 1996, 1997, 2000, 2003, 2005

hydra

n (Zool, Myth) → Hydra f

Collins German Dictionary – Complete and Unabridged 7th Edition 2005. © William Collins Sons & Co. Ltd. 1980 © HarperCollins Publishers 1991, 1997, 1999, 2004, 2005, 2007

References in periodicals archive ?

Rahat and Reich (1985) described the endosymbiotic relationship between vulgaris group hydras and green algae, and at that time they suggested that the symbiotic algae belonged to the genus Chlorococcum; a few years later those authors described the symbiotic green algae as Symbiococcum hydrae gen.

Zoospore formation by Symbiococcum hydrae (Chlorosarcinales.

Horizontal Transmission of Symbiotic Green Algae Between Hydra Strains

As it turns out, central Hydra has two of the best carbon stars for binos: U and V Hydrae. The pair straddles 3.1-magnitude Nu (v) Hydrae, one of the constellation's leading lights.

Hydra hits

At 10 million years of age, TW Hydrae fit the bill.

Pebbles from heaven: tracking planets in the making

Procyon and Regulus form a nearly right triangle with Alphard (Alpha Hydrae), the lonely, orange, 2nd-magnitude heart of Hydra the Sea Serpent.

Treasures of Puppis & Hydra: many lesser-known treats adorn these constellations

Indeed, astronomers exploring the closest of these star groups, dubbed the TW Hydrae association, unveiled an image 2 years ago that may be a baby planet (SN: 1/9/99, p.

Captured on Camera: Are They Planets?

Hydra's brightest star is 2nd-magnitude Alpha ([alpha]) Hydrae, popularly known as Alphard.

Constellations big and small: June evenings offer contrasting constellations

As we've drawn Hydra, the tip of the tail is an unmarked dim star, 58 Hydrae, and the figure is 95[degrees] long (not following its bends, but taking the shortest, or great-circle, route between ends).

The long and short of it: can you guess which constellation is 22 times longer than which other?

To locate M48, look for 3.9-magnitude C Hydrae 8[degrees] south-southwest of Hydra's head.

Highlights of hydra

Using the map above, start at Alphard, Alpha (a) Hydrae, and carefully trace your way eastward along Hydra's winding form until you are aimed midway along the line from Mu (m) to Nu (n) Hydrae.

U and V Hydrae

South of Spica by 12 [degrees] lies 3rd-magnitude Gamma ([Gamma]) Hydrae, a useful guide star for finding a remarkable long-period variable.