The Collaborative International Dictionary of English v.0.48:

Echidna \E*chid"na\ ([-e]*k[i^]d"n[.a]), n. [L., a viper, adder,
   Gr. 'e`chidna.]
   1. (Gr. Myth.) A monster, half maid and half serpent.
      [1913 Webster]

   2. (Zo["o]l.) A genus of Monotremata found in Australia,
      Tasmania, and New Guinea. They are toothless and covered
      with spines; -- called also porcupine ant-eater, and
      Australian ant-eater.
      [1913 Webster]

WordNet (r) 3.0 (2006):

echidna
    n 1: a burrowing monotreme mammal covered with spines and having
         a long snout and claws for hunting ants and termites;
         native to New Guinea [syn: echidna, spiny anteater,
         anteater]
    2: a burrowing monotreme mammal covered with spines and having a
       long snout and claws for hunting ants and termites; native to
       Australia [syn: echidna, spiny anteater, anteater]

The Free On-line Dictionary of Computing (30 December 2018):

Echidna

   Constraint logic programming embedded in an
   object-oriented language.  The syntax is an extension of
   Edinburgh Prolog.

   ["Hierarchical Arc Consistency Applied to Numeric Processing
   in Constraint Logic Programming", G. Sidebottom et al,
   TR-91-06, CSS-IS, Simon Fraser U, and Comp Intell 8(4)
   (1992)].

   (ftp://cs.sfu.edu/pub/ecl/papers).

   E-mail: .

   (1994-12-08)