Hydra

noun

Hy·​dra ˈhī-drə 

1

: a many-headed serpent or monster in Greek mythology that was slain by Hercules and each head of which when cut off was replaced by two others

2

not capitalized : a multifarious evil not to be overcome by a single effort

3

: a southern constellation of great length that lies south of Cancer, Sextans, Corvus, and Virgo and is represented on old maps by a serpent

4

not capitalized : any of numerous small tubular freshwater hydrozoan polyps (Hydra and related genera) having at one end a mouth surrounded by tentacles

Word History

Etymology

Middle English Ydra, Idre, borrowed from Latin Hydra "any of various mythical monsters, especially the Hydra of Lerna killed by Hercules, a constellation," borrowed from Greek hýdra "aquatic snake, the Hydra of Lerna, a constellation"; (sense 4) borrowed from New Latin, genus name, going back to Latin — more at otter

First Known Use

15th century, in the meaning defined at sense 1

Kids Definition

hydra

noun

hy·​dra

ˈhī-drə

: any of numerous small tube-shaped freshwater animals related to the jellyfishes and having a mouth surrounded by tentacles at one end

Medical Definition

hydra

noun

hy·​dra ˈhī-drə 

: any of numerous small tubular freshwater hydrozoan polyps (Hydra and related genera) having at one end a mouth surrounded by tentacles

Geographical Definition

Hydra

geographical name

Hy·​dra ˈhī-drə 

variants or Modern Greek Ídhra

ˈēt͟h-rä 

island of Greece in the southern Aegean Sea off the east coast of the Peloponnese area 20 square miles (52 square kilometers), population 2794

Hydriot

ˈhī-drē-ət 

-drē-ˌät

noun

or Hydriote

ˈhī-drē-ˌōt 

-ət