bombinate

bombinate \BOM-buh-nayt\, intransitive verb:

To buzz; to hum; to drone.

He is often drunk. His head hurts. Snatches of conversation, remembered precepts, prefigured cries of terror bombinate about his skull.
-- Elspeth Barker, "Nobs and the rabble, all in the same boat", Independent, September 22, 1996

Sometimes the computer bombinates way into the night, stops for a bit of rest, then resumes its hum at the early hours of the morning.
-- Cheryl Glenn and Robert J. Connors, New St. Martins Guide to Teaching Writing

Bombinate is from Late Latin bombinatus, past participle of bombinare, alteration of Latin bombilare, from bombus, "a boom."