Flutter, v. t.
1. To vibrate or move quickly; as, a bird flutters its wings.
2. To drive in disorder; to throw into confusion. Like an eagle in a dovecote, I Fluttered your Volscians in Corioli. Shak.
1 other Webster entry under this spelling
Flutter, n.
1. The act of fluttering; quick and irregular motion; vibration; as, the flutter of a fan. The chirp and flutter of some single bird Milnes. .
2. Hurry; tumult; agitation of the mind; confusion; disorder. Pope. Flutter wheel, a water wheel placed below a fall or in a chute where rapidly moving water strikes the tips of the floats; -- so called from the spattering, and the fluttering noise it makes.
Shades of meaning
Fernald has no entry of its own for flutter; he lists it under shake.
Where he writes about it:
Flap, flutter, and fluctuate refer to wave-like movements, flap generally to such as produce a sharp sound; a cock flaps his wings; flutter applies to a less pronounced and more irregular motion; a captive bird or a feeble pulse flutters. — from shake