The Collaborative International Dictionary of English v.0.48:

Blather \Blath"er\ (bl[a^][th]"[~e]r), v. i. & t. [imp. & p. p.
   Blathered; p. pr. & vb. n. Blathering.] [Written also
   blether.] [Icel. bla[eth]ra. Cf. Blatherskite.]
   To talk foolishly, or nonsensically, or concerning matters of
   no consequence. --G. Eliot.

   Syn: babble, smatter, blether, blither.
        [Webster 1913 Suppl. + WordNet 1.5]