The Collaborative International Dictionary of English v.0.48:

Asyndeton \A*syn"de*ton\, n. [L., fr. Gr. ?, fr. ? unconnected;
   'a priv. + ? bound together, fr. ?; ? with + ? to bind.]
   (Rhet.)
   A figure which omits the connective; as, I came, I saw, I
   conquered. It stands opposed to polysyndeton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

asyndeton
    n 1: the omission of conjunctions where they would normally be
         used