The Collaborative International Dictionary of English v.0.48:

Elench \E*lench"\ ([-e]*l[e^][ng]k"), n.; pl. Elenchs. [L.
   elenchus, Gr. ?, fr. ? to convict, confute, prove: cf. OF.
   elenche.] (Logic)
   (a) That part of an argument on which its conclusiveness
       depends; that which convinces of refutes an antagonist; a
       refutation.
   (b) A specious but fallacious argument; a sophism.
       [1913 Webster]