verb Of a winged animal: to flap the wings without flying; to fly with a light flapping of the wings.
verb To undergo divergent oscillations (potentially to the point of causing structural failure) due to a positive feedback loop between elastic deformation and aerodynamic forces.
verb To cause something to flap.
A bird flutters its wings.
verb To drive into disorder; to throw into confusion.
verb To be in a state of agitation or uncertainty.