From WordNet (r) 3.0 (2006):
drone
n 1: stingless male bee in a colony of social bees (especially
honeybees) whose sole function is to mate with the queen
2: an unchanging intonation [syn: monotone, drone,
droning]
3: someone who takes more time than necessary; someone who lags
behind [syn: dawdler, drone, laggard, lagger,
trailer, poke]
4: an aircraft without a pilot that is operated by remote
control [syn: drone, pilotless aircraft, radio-
controlled aircraft]
5: a pipe of the bagpipe that is tuned to produce a single
continuous tone [syn: drone, drone pipe, bourdon]
v 1: make a monotonous low dull sound; "The harmonium was
droning on"
2: talk in a monotonous voice [syn: drone, drone on]