To flap or wave quickly but irregularly.
flags fluttering in the wind
Of a winged animal: to flap the wings without flying; to fly with a light flapping of the wings.
To cause something to flap.
A bird flutters its wings.
To drive into disorder; to throw into confusion.
To be in a state of agitation or uncertainty.
To be frivolous.
Rapid back-and-forth waving or oscillation.