fluttering

verb
  1. 1

    To flap or wave quickly but irregularly.

    โ€œflags fluttering in the windโ€

  2. 2

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

  3. 3

    To cause something to flap.

    โ€œA bird flutters its wings.โ€

  4. 4

    To drive into disorder; to throw into confusion.

  5. 5

    To be in a state of agitation or uncertainty.

  6. 6

    To be frivolous.

noun
  1. 1

    Rapid back-and-forth waving or oscillation.

Source: https://en.wiktionary.org/wiki/flutter, https://en.wiktionary.org/wiki/fluttering