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]

The Collaborative International Dictionary of English v.0.48:

Blather \Blath"er\, n. [Written also blether.]
   Voluble, foolish, or nonsensical talk; -- often in the pl.
   --Hall Caine.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

blether
    n 1: idle or foolish and irrelevant talk [syn: prate,
         prattle, idle talk, blether, chin music]
    v 1: to talk foolishly; "The two women babbled and crooned at
         the baby" [syn: babble, blather, smatter, blether,
         blither]