drone

stingless male bee in a colony of social bees (especially honeybees) whose sole function is to mate with the queen

an unchanging intonation

someone who takes more time than necessary; someone who lags behind

an aircraft without a pilot that is operated by remote control

a pipe of the bagpipe that is tuned to produce a single continuous tone

make a monotonous low dull sound; "The harmonium was droning on"

talk in a monotonous voice