verb

make a continuous low humming sound.

in the far distance a machine droned

hum,buzz,whir,vibrate,murmur,rumble,purr,hiss,whisper,sigh

noun

a continuous low humming sound.

he nodded off to the drone of the car engine

hum,buzz,whir,whirring,vibration,murmur,murmuring,purr,purring,hiss,hissing,whisper,whispering,sigh