Source : Webster's Revised Unabridged Dictionary (1913)

Buzzer \Buzz"er\ (b[u^]z"[~e]r), n.
   One who, or that which, buzzes; a whisperer; a talebearer.

         And wants not buzzers to infect his ear With pestilent
         speeches of his father's death.          --Shak.

Source : WordNet®

buzzer
     n 1: a push button at an outer door that gives a ringing or
          buzzing signal when pushed [syn: {doorbell}, {bell}]
     2: a signaling device that makes a buzzing sound