What is "hydra"

Hydra \Hy"dra\, n.; pl. E. Hydras, L. Hydr[ae]. [L. hydra, Gr. "y`dra; akin to "y`dwr water. See Otter the animal, Water.]

1. (Class. Myth.) A serpent or monster in the lake or marsh of Lerna, in the Peloponnesus, represented as having many heads, one of which, when cut off, was immediately succeeded by two others, unless the wound was cauterized. It was slain by Hercules. Hence, a terrible monster.

   Gorgons, and Hydras, and Chimeras dire.
   --Milton.

2. Hence: A multifarious evil, or an evil having many sources; not to be overcome by a single effort.

3. (Zo["o]l.) Any small fresh-water hydroid of the genus Hydra, usually found attached to sticks, stones, etc., by a basal sucker.

   Note: The body is a simple tube, having a mouth at one extremity, surrounded by a circle of tentacles with which it captures its prey. Young hydras bud out from the sides of the older ones, but soon become detached and are then like their parent. Hydras are remarkable for their power of repairing injuries; for if the body be divided in pieces, each piece will grow into a complete hydra, to which fact the name alludes. The zooids or hydranths of marine hydroids are sometimes called hydras.

4. (Astron.) A southern constellation of great length lying southerly from Cancer, Leo, and Virgo.

1835, genus name of a freshwater polyp, from Greek Hydra, many-headed Lernaean water serpent slain by Hercules (this sense is attested in English from late 14c.), from hydor "water" (see water (n.1)); related to Sanskrit udrah "aquatic animal" and Old English ottur "otter." Used figuratively for "any multiplicity of evils" [Johnson]. The fabulous beast's heads were said to grown back double when cut off, and the sea creature is said to be so called for its regenerative capabilities.

n. 1 Any of several small freshwater polyps of the genus ''Hydra'' and related genera, having a naked cylindrical body and an oral opening surrounded by tentacles. 2 A complex, multifarious problem or situation that cannot be solved easily and rapidly.

Hydra is a genus of small, fresh-water animals of the phylum Cnidaria and class Hydrozoa, native to the temperate and tropical regions. Biologists are especially interested in Hydra because of their regenerative ability – they appear not to age or die of old age.

Hydra (, pronounced in modern Greek) is one of the Saronic Islands of Greece, located in the Aegean Sea between the Saronic Gulf and the Argolic Gulf. It is separated from the Peloponnese by a narrow strip of water. In ancient times, the island was known as Hydrea (Υδρέα, derived from the Greek word for "water"), a reference to the springs on the island.

The municipality of Hydra consists of the islands Hydra (area ), Dokos (pop. 18, area ), and a few uninhabited islets. The province of Hydra was one of the provinces of the Piraeus Prefecture. Its territory corresponded with that of the current municipality. It was abolished in 2006.

There is one main town, known simply as "Hydra port" (pop. 1,900 in 2011). It consists of a crescent-shaped harbor, around which is centered a strand of restaurants, shops, markets, and galleries that cater to tourists and locals (Hydriots). Steep stone streets lead up and outward from the harbor area. Most of the local residences, as well as the hostelries on the island, are located on these streets. Other small villages or hamlets on the island include Mandraki (pop. 11), Kamini, Vlychos (19), Palamidas, Episkopi, and Molos.

Hydra is the largest of the 88 modern constellations, measuring 1303 square degrees. Also one of the longest at over 100 degrees, its southern end abuts Libra and Centaurus and its northern end borders Cancer. It has a long history, having been included among the 48 constellations listed by the 2nd century astronomer Ptolemy. It is commonly represented as a water snake. It should not be confused with the similarly named constellation of Hydrus.

Hydra may refer to:

• Lernaean Hydra, a many-headed serpent in Greek mythology
• Hydra (genus), a genus of simple freshwater animals belonging to the phylum Cnidaria

Hydra is a fictional terrorist organization appearing in American comic books published by Marvel Comics. The name "Hydra" is a reference to the mythical Lernaean Hydra. The organization's motto references the myth of the Hydra, stating that "if a head is cut off, two more will take its place", proclaiming their resilience and growing strength in the face of resistance. Hydra agents often wear distinctive green garb featuring a serpent motif.

Hydra is the outermost known moon of Pluto. It was discovered along with Nix in June 2005, and was visited along with Pluto by New Horizons in July 2015. Hydra's surface is probably covered with water ice. Observed within Hydra's bright regions is a darker circular structure with a diameter of approximately 10 kilometers (5 miles). Hydra's reflectivity (the percentage of incident light reflected from the surface) is intermediate between those of Pluto and Charon.

Hydra is the second studio album by American rock band Toto, released in 1979. It reached #37 on the Billboard Pop Albums. While most of the album's singles failed to make any impact in the charts, " 99", a song inspired by the 1971 science fiction movie THX 1138, reached #26 on the Billboard Hot 100.

Hydra was a chess machine, designed by a team with Dr. Christian "Chrilly" Donninger, Dr. Ulf Lorenz, GM Christopher Lutz and Muhammad Nasir Ali. Since 2006 the development team consisted only of Donninger and Lutz. Hydra was under the patronage of the PAL Group and Sheikh Tahnoon Bin Zayed Al Nahyan of Abu Dhabi. The goal of the Hydra Project was to dominate the computer chess world, and finally have an accepted victory over humans.

Hydra represented a potentially significant leap in the strength of computer chess. Design team member Lorenz estimates its FIDE equivalent playing strength to be over Elo 3000, and this is in line with its results against Michael Adams and Shredder 8, the former micro-computer chess champion.

Hydra began competing in 2002 and played its last game in June 2006. In June 2009, Christopher Lutz stated that "unfortunately the Hydra project is discontinued." The sponsors decided to end the project.

In the Dungeons & Dragons fantasy roleplaying game, the hydra is a reptilian magical beast with anywhere from five to twelve heads.

HYDRA was an early capability-based, object-oriented, microkernel designed to support a wide range of possible operating systems to run on top of it. HYDRA was created as part of the C.mmp project at Carnegie-Mellon University in 1971.

HYDRA was designed to be modular and secure, and intended to be flexible enough for easy experimentation. The system was implemented in the programming language BLISS.

Hydra is an American Southern rock band founded in the late 1960s by Spencer Kirkpatrick (guitar), Wayne Bruce (vocals and guitar), and Steve Pace (drums). In 1977, it became a three-piece band (with Wayne Bruce now on bass) and the band broke up later that year. It released three albums, Hydra (1974), Land of Money (1975) and Rock the World (1977). In 2005, the band reunited for two shows (with Vickery on bass). A live album, Hydra: Live After All These Years was released.

The Hydra is a 22-person hydrogen ship, power-assisted by an electric motor that gets its electricity from a fuel cell. The debut was in June 2000 on the Rhine near Bonn, Germany.

The idea for this project came from Christian Machens in 1999 for designing and building the fuel cell system for the Hydra in Leipzig.

The ship transported around 2.000 passengers in 1999/2000 and was used as a ferry-boat in Ghent, Belgium during an electric boat conference in 2000. It was fully certified by the Germanischer Lloyd for passenger transport and the fuel cell system had the ability to start even at temperatures below the freezing point.

The boat was withdrawn from service in 2001.

Hydra is the third studio album by the melodic death metal band Satariel. Pär Johansson's clean vocals are used more frequently than in their previous CDs.

The modern constellation Hydra lies across two of the quadrants, symbolized by the Azure Dragon of the East (東方青龍, Dōng Fāng Qīng Lóng) and the Vermilion Bird of the South (南方朱雀, Nán Fāng Zhū Què), that divide the sky in traditional Chinese uranography.

The name of the western constellation in modern Chinese is 長蛇座 (cháng shé zuò), which means "the long snake constellation".

Hydra (also known as Hydra: The Lost Island) is a 2009 low-budget monster movie by Andrew Prendergast and Peter Sullivan, which blends elements of horror, thriller and classical mythology. It was made for cable TV and subsequently internationally distributed on DVD.

Hydra is the sixth studio album by the heavy metal band Otep. It was released in 2013 on Victory Records. Hydra is a concept album. This is the first album to feature drum programming as opposed to live drums.

Hydra is an open-source digital repository software product. Hydra's main components are Fedora Commons, Solr, Blacklight, and HydraHead (a Ruby on Rails plugin and gem, respectively). Each Hydra implementation is called a "Hydra head".

Jennifer Wilson, known as Hydra, is a roller derby skater who has played a leading role in the development of the sport.

Hydra joined Bad Girl Good Woman (BGGW) in 2001, around the time that the league was founded. She worked as a hydrologist and selected her derby name in reference both to this, and to the mythological monster. She played a leading role in the team, utilising her experience as a high-level American handball player. later joining its Texas Rollergirls split. She played for Texas in Phoenix, AZ, against the Arizona Roller Derby in 2003, winning the first ever flat track intraleague bout.

Hydra was the creator of the Master Roster of roller derby skater names, maintaining the registry until she transferred the duties in 2005.

Hydra was a founder member of the United Leagues Coalition (ULC), and in 2004 was already envisaging it becoming a national governing body. The ULC later became the Women's Flat Track Derby Association (WFTDA), and she served as the WFTDA's first president. She captained the Texas team which won the 2006 WFTDA Championship. The WFTDA championship trophy is named the Hydra Trophy in her honor.

Hydra stood down as WFTDA President in 2007, but served on its Board of Directors until the end of 2009. In 2010, she was still playing roller derby, for the Texas Rollergirls Rec-n-Roller Derby.

Hydra is the sixth studio album by Dutch symphonic metal band Within Temptation. It was released on January 31, 2014 in Europe and on February 4, 2014 in North America. The album contains guest appearances by singer Howard Jones (ex- Killswitch Engage), rapper Xzibit, metal vocalist Tarja Turunen (ex- Nightwish) and alternative rock singer Dave Pirner ( Soul Asylum). The first single, " Paradise (What About Us?)", was released on September 27, 2013, and featured Turunen as guest vocalist. The second single, " Dangerous", was released on December 20, in which Jones provided the male vocals.

This is the first album by Within Temptation to be recorded with three guitarists, with Stefan Helleblad making his Within Temptation studio debut on Hydra since his addition to the band shortly after the release of The Unforgiving in 2011. Hydra is also the first Within Temptation album to feature Robert Westerholt's growling techniques since the band's debut album, Enter.