Echidna . ( Junction of the Gr. ?, Viper, and?, hedgehog). 1. m. mammal monotrema, insectivore, small head, sharp snout, long and very extensible language with spines. The neck, tail and legs are short; fingers, equipped with strong claws to dig; the body, covered with dark hair, between leaving a few spikes on the back and the sides, similar to the Hedgehog.