(non-technical) Especially, any of the insects of the family Muscidae, such as the common housefly (other families of Diptera include mosquitoes and midges).
Two or more vanes set on a revolving axis, to act as a fanner, or to equalize or impede the motion of machinery by the resistance of the air, as in the striking part of a clock.
A heavy wheel, or cross arms with weights at the ends on a revolving axis, to regulate or equalize the motion of machinery by means of its inertia, where the power communicated, or the resistance to be overcome, is variable, as in the steam engine or the coining press. See flywheel.