Source : Webster's Revised Unabridged Dictionary (1913)

Bombilate \Bom"bi*late\, v. i. [LL. bombilare, for L. bombitare.
   See {Bomb}, n.]
   To hum; to buzz. [R.]

Source : WordNet®

bombilate
     v : make a buzzing sound; "bees were buzzing around the hive"
         [syn: {buzz}, {bombinate}]