flutter

verb

1. (intransitive)To flap or wave quickly but irregularly.

   “flags fluttering in the wind”

   “Long after his cigar burnt bitter, he sat with eyes fixed on the blaze. When the flames at last began to flicker and subside, his lids fluttered, then drooped ; but he had lost all reckoning of time when he opened them again to find Miss Erroll in furs and ball-gown kneeling on the hearth and heaping kindling on the coals, [...]”

2. (intransitive)Of a winged animal: to flap the wings without flying; to fly with a light flapping of the wings.

   “Banks of gorgeous flowers were on every hand, and birds with rare and brilliant plumage sang and fluttered in the trees and bushes.”

3. (intransitive)To undergo divergent oscillations (potentially to the point of causing structural failure) due to a positive feedback loop between elastic deformation and aerodynamic forces.
4. (transitive)To cause something to flap.

   “A bird flutters its wings.”

5. (transitive)To drive into disorder; to throw into confusion.

   “If you haue vvrit your Annales true, 'tis there, / That like an Eagle in a Doue-cote, I / Flatter'd^([sic – meaning Flutter'd]) your Volcians in Corioles.”

   “There was a clearness of expression in this, and a downright surrender of himself, which so flattered her and so fluttered her that she was almost reduced to the giving of herself up because she could not reply to such an appeal in language less courteous than that of agreement”

6. (intransitive)To be in a state of agitation or uncertainty.

   “It was fluttering with nervousness like a human heart. He was all in a sweat with fear, and—do you know, I don't believe the rascal is a Robot at all any longer.”

7. (intransitive, obsolete)To be frivolous.
8. (slang)To subject to a lie detector test.

   “This was the first time that Nosenko had been subjected to a lie detector — or what the CIA called fluttering. The Soviet Union did not use such devices for interrogation.”

   “"Anyway, she cracked and we fluttered her and—" / "Fluttered her?" / "Sorry, gave her a polygraph, a lie detector test. And she passed, more or less, […]”

noun

1. (countable, uncountable)The act of fluttering; quick and irregular motion.

   “the flutter of a fan”

   “the chirp and flutter of some single bird”

2. (countable, uncountable)A state of agitation.

   “flutter of spirits”

   “Their visitor was an issue - at least to the imagination, and they arrived finally, under provocation, at intensities of flutter in which they felt themselves so compromised by his hoverings that they could only consider with relief the fact of nobody's knowing.”

3. (countable, uncountable)An abnormal rapid pulsation of the heart.
4. (uncountable)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.
5. (British, countable, uncountable)A small bet or risky investment.

   “"Oh, by the way, I heard of a rather good thing today, New Kleinfonteins; it's a gold mine in Rhodesia. If you'd like to have a flutter you might make a bit."”

   “30 July, 2009, Eurosport, Gray Matter: How will Schu do? So with his victory odds currently at 14/1 or 3/1 for the podium, he's still most certainly well worth a flutter […]”

6. (countable, uncountable)A hasty game of cards or similar.
7. (countable, uncountable)The rapid variation of signal parameters, such as amplitude, phase, and frequency.