Source : Webster's Revised Unabridged Dictionary (1913)

Chitter \Chit"ter\, v. i. [Cf. {Chatter}.]
   1. To chirp in a tremulous manner, as a bird. [Obs.]
      --Chaucer.

   2. To shiver or chatter with cold. [Scot.] --Burns.

Source : WordNet®

chitter
     v : make high-pitched sounds, as of birds [syn: {twitter}]