The Hydra Grew Two Heads for Every One Cut Off
A hydra is a many-headed monster of Greek myth. It also names a real freshwater animal that can regenerate its whole body.
A hydra is the many-headed serpent of Greek myth killed by Heracles, and by extension any problem that multiplies when attacked. The name was given to a real animal for good reason: the freshwater *Hydra* is a tiny tentacled creature that regenerates so completely that a fragment can grow into a whole animal, and it shows no signs of ageing. The Greek *hydra* simply means water serpent, from *hydor*, water.
- A mythical monster. *The Lernaean Hydra.*
- A multiplying problem. *A hydra-headed crisis.*
- A freshwater animal. *A hydra under the microscope.*
- Hydrant, hydrate, hydraulic — from the same root. *A fire hydrant.*
- Greek — *hydor*, water. *The source.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | hydra | A hydra. |
| Plural | hydras | Two hydras. |
| Latin plural | hydrae | Hydrae. |
| Adjective | hydra-headed | Hydra-headed. |
| Greek | hydor | Water. |
- Heracles burned each neck to stop regrowth.Myth.
- The hydra regenerates from fragments.Biology.
- A hydra-headed problem.Figurative.
The hydor family
- Hydrant — a water outlet
- Hydrate — to add water
- Hydraulic — operated by liquid pressure
- Hydrogen — the water-former, named for producing water when burned
- Dehydrate — to remove water
Greek *hydra*, a water serpent, from *hydor*, water. The biological genus was named in the 1700s for its regenerative power.
Can a real hydra regenerate?
Yes. The freshwater hydra can regrow a complete animal from a small fragment and shows no measurable ageing.
Why is hydrogen named after water?
Because it produces water when it burns. The name means water-former.