Middle English drane, drone, "male honeybee," from Old English dran, dræn, from Proto-Germanic *dran- (source also of Middle Dutch drane; Old High German treno; German Drohne, which is from Middle Low German drone), probably imitative (compare Lithuanian tranni, Greek thronax "a drone"). Given a figurative sense of "idler, lazy worker" (male bees make no honey) 1520s. Meaning "pilotless aircraft directed by remote control" is from 1946.
Drones, as the radio-controlled craft are called, have many potentialities, civilian and military. Some day huge mother ships may guide fleets of long-distance, cargo-carrying airplanes across continents and oceans. Long-range drones armed with atomic bombs could be flown by accompanying mother ships to their targets and in for perfect hits. [Popular Science, November 1946]
Meaning "a deep, continuous humming sound" is from c. 1500, apparently an independent imitative formation (compare threnody). Meaning "bass pipe of a bagpipe" is from 1590s.
mid-14c., drounen, "to roar, bellow;" c. 1500, "to give forth a monotonous and unvaried tone, hum, or buzz," imitative (see drone (n.)). In modern times it often is the characteristic sound of airplane engines. Meaning "speak in a dull, monotonous tone" is from 1610s. Related: Droned; droning.