v (intransitive) To flap or wave quickly but irregularly.
v (intransitive) Of a winged animal: to flap the wings without flying; to fly with a light flapping of the wings.
v (intransitive, aerodynamics) To undergo divergent oscillations (potentially to the point of causing structural failure) due to a positive feedback loop between elastic deformation and aerodynamic forces.
v (transitive) To cause something to flap.
v (transitive) To drive into disorder; to throw into confusion.
v (intransitive) To be in a state of agitation or uncertainty.
v (intransitive, obsolete) To be frivolous.
v (espionage, slang) To subject to a lie detector test.
n The act of fluttering; quick and irregular motion.
n A state of agitation.
n An abnormal rapid pulsation of the heart.
n (uncountable, aerodynamics) An extremely dangerous divergent oscillation caused by a positive feedback loop between the elastic deformation of an object and the aerodynamic forces acting on it, potentially resulting in rapid structural failure.
n (Britain) A small bet or risky investment.
n A hasty game of cards or similar.
n (audio, electronics) The rapid variation of signal parameters, such as amplitude, phase, and frequency.