Definition of echidna
- a spiny insectivorous egg-laying mammal with a long snout and claws, native to Australia and New Guinea. Also called spiny anteater.
- Family Tachyglossidae, order Monotremata: two genera and species
mid 19th century: modern Latin, from Greek ekhidna 'viper', also the name of a mythical creature which gave birth to the Hydra; compare with ekhinos 'sea urchin, hedgehog'