The Collaborative International Dictionary of English v.0.48:

Blurt \Blurt\ (bl[^u]rt), v. t. [imp. & p. p. Blurted; p. pr.
   & vb. n. Blurting.] [Cf. Blare.]
   To utter suddenly and unadvisedly; to divulge
   inconsiderately; to ejaculate; -- commonly with out.
   [1913 Webster]

         Others . . . can not hold, but blurt out, those words
         which afterward they are forced to eat.  --Hakewill.
   [1913 Webster]

   To blurt at, to speak contemptuously of. [Obs.] --Shak.
      [1913 Webster]