drone

verb

• make a continuous low humming sound:in the far distance a machine droned
• speak tediously in a dull monotonous tone:he reached for another beer while Jim droned on
• [with adverbial of direction] move with a continuous humming sound:traffic droned up and down the street

noun

• 1a low continuous humming sound:he nodded off to the drone of the car engine
• informal a monotonous speech:only twenty minutes of the hour-long drone had passed
• a continuous musical note, typically of low pitch.
• a musical instrument, or part of one, sounding a continuous note, in particular (also drone pipe) a pipe in a bagpipe or (also drone string) a string in an instrument such as a hurdy-gurdy or a sitar.

• 2a male bee in a colony of social bees, which does no work but can fertilize a queen.
• a person who does no useful work and lives off others.

• 3a remote-controlled pilotless aircraft or missile.