hydra
noun
Often Hydra 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.
hydra
American
[hahy-druh]
/ ˈhaɪ drə /
noun
-
hydras,
plural
-
hydrae,
plural
-
Hydrae
genitive
-
Classical Mythology. Often Hydra 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) the Sea Serpent, a large southern constellation extending through 90° of the sky, being the longest of all constellations.
Hydra
1
British
/ ˈhaɪdrə /
noun
Hydra
2
British
/ ˈhaɪdrə /
noun
hydra
3
British
/ ˈhaɪdrə /
noun
-
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
hydra
Scientific
/ hī′drə /
-
hydras
plural
Other Word Forms
Noun Inflected Forms
Etymology
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
Vocabulary lists containing hydra
Elements of the Universe: Hydr, Hydro ("Water")
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Reading: Literature - Mythology - Introductory
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Reading: Literature - Mythology - Middle School
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
"In 20 years, and despite the resolute efforts of our police officers, gendarmes, judges, teachers and elected officials, the antisemitic hydra has kept advancing," he said.
From Barron's ● Feb. 13, 2026
Aside from giving housing and homelessness their own box atop Newsom’s organizational chart, the chief selling point of the reorganization has been to simplify the state’s hydra of affordable housing financing systems.
From Los Angeles Times ● Jul. 13, 2025
This suggests that evolution plays around with these chemical pathways, altering them over the hundreds of millions of years since the hydra and human lineages diverged from each other on the evolutionary tree.
From Scientific American ● Jun. 16, 2023
"Greek football is a hydra with many heads. You cut one, others emerge."
From BBC ● Feb. 23, 2022
He rolled to one side as all eight hydra heads spit acid, turning the floor where he’d been standing into a steaming crater of melted stone.
From "The Mark of Athena" by Rick Riordan
On an obscure research assignment, the narrator travels to the Greek island of Hydra to meet Theódoros Apostolakis, who has created a paradoxical museum for lost things.
From The Wall Street Journal ● Aug. 4, 2026
In April 2022, the German federal police, acting on information from their American colleagues, seized the servers hosting Hydra, replacing its banner with their logo and retrieving $25 million in Bitcoin.
From Salon ● Nov. 14, 2024
The Marvel universe more recently used the Nazi-like Hydra organization as a multiheaded big bad.
From New York Times ● Jun. 19, 2024
High sensitivity radio observations have discovered a cloud of magnetized plasma in the Hydra galaxy cluster.
From Science Daily ● Apr. 8, 2024
The Hydra was only a few feet away.
From "The Sea of Monsters" by Rick Riordan
On the topic of aging, Earth does actually have organisms that are functionally immortal, such as hydras.
From Scientific American ● May 28, 2023
Budding occurs commonly in some invertebrate animals such as corals and hydras.
From Textbooks ● Jun. 9, 2022
"Online services are like hydras, if you fix one problem, another one often emerges," James Mickens, a professor of computer science at Harvard, explains in a statement.
From BBC ● Sep. 9, 2021
Everyone in New York has heard about co-op boards that proved to be the most persnickety of the many many-headed hydras exerting authority over daily life.
From New York Times ● May 8, 2016
There were miniature lions, pigs, dragons, hydras, even a teeny Minotaur in a little Minotaur diaper.
From "The Last Olympian" by Rick Riordan
The infalling matter collides with other material bound to the white dwarf, forming tall columns of hot gas that emit intense X-rays, making systems like EX Hydrae ideal targets for IXPE.
From Science Daily ● Jan. 8, 2026
In EX Hydrae, the magnetic field is not strong enough to direct all incoming material onto the star's magnetic poles.
From Science Daily ● Jan. 8, 2026
EX Hydrae exists in a binary system alongside a normal main sequence star.
From Science Daily ● Jan. 8, 2026
The mission's ability to measure the polarization of X-rays allowed astronomers to closely examine EX Hydrae, a type of system known as an intermediate polar.
From Science Daily ● Jan. 8, 2026
They have a model, a most ingenious affair run by clockwork, at the University of Konkrook, to show the apparent movement and position of Beta Hydrae in the sky; it does so fairly accurately.
From Uller Uprising by John D. Clark
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
