flap

noun
  1. A piece of material that is attached on one side and hangs loosely or covers an opening. noun
    The envelope had a flap that needed to be sealed.
    She lifted the flap of the tent to look outside.
  2. A state of agitation or panic. noun
    There was a flap in the office when the news broke.
    She got into a flap when she realized she was late.
  3. To move up and down or back and forth quickly and noisily. verb
    The bird began to flap its wings vigorously.
    The flag flapped in the strong wind.
  4. To cause something to move or sway with a flapping motion. verb
    He flapped the towel to dry it faster.
    The child flapped the book open and closed.