flutter

1. (v) (intransitive) To flap or wave quickly but irregularly. 2. (v) (intransitive) Of a winged animal: to flap the wings without flying; to fly with a light flapping of the wings. 3. (v) (intransitive) To be in a state of agitation or uncertainty. 4. (n) The act of fluttering; quick and irregular motion. 5. (n) A state of agitation. 6. (n) An abnormal rapid pulsation of the heart. 7. (v) (transitive) To cause something to flap. 8. (v) (transitive) To drive into disorder; to throw into confusion. 9. (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. 10. (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. 11. (n) (British) A small bet or risky investment. 12. (n) A hasty game of cards or similar. 13. (n) (audio, electronics) The rapid variation of signal parameters, such as amplitude, phase, and frequency. 14. (v) (espionage, slang) To subject to a lie detector test. 15. (v) (intransitive, obsolete) To be frivolous.