bombilation

from WordNet (r) 3.0 (2006)

bombilation
    n 1: sound of rapid vibration; "the buzz of a bumble bee" [syn:
         {buzz}, {bombilation}, {bombination}]

from The Collaborative International Dictionary of English v.0.48

Bombilation \Bom`bi*la"tion\, n.
   A humming sound; a booming.
   [1913 Webster]

         To . . . silence the bombilation of guns. --Sir T.
                                                  Browne.
   [1913 Webster]