Is there any difference between flap and flutter?


The bird is flapping its wings.

The bird is fluttering its wings.


Etymologically, the verb to flap is related to the noun flap. A flap is something that hangs free at one end, and is fixed at the other. From Merriam-Webster:

something that is broad, limber, or flat and usually thin and that hangs loose or projects freely: such as

a : a piece on a garment that hangs free

b : a part of a book jacket that folds under the book's cover

c : a piece of tissue partly severed from its place of origin for use in surgical grafting

d : an extended part forming the closure (as of an envelope or carton)

The act of moving this loose end up and down along its join is flapping, perhaps onomatopoeic from the resultant sound.

A flutter is a very light and rapid flapping motion. Speed and agility distinguish a flutter from a flap. You might say that a hummingbird or a butterfly flutters its wings, since both of those are small and agile creatures with rapid wing motions.

Technically, you could also say that the hummingbird flies by flapping its wings, since the fluttering is accomplished by moving its wing up and down, i.e., by flapping. However, the swiftness and relative quietness of the motion makes flutter the more usual choice. Google Ngrams shows zero results for "hummingbird flapping" as opposed to "hummingbird fluttering".

But you would not say an eagle or a hawk flutters its wings. You would say flap, because the movement is too slow to qualify as a flutter. Google Ngrams again shows zero results for "eagle fluttering" as opposed to "eagle flapping".

A sail that's fluttering in the wind is moving rather more quickly and quietly than one that's flapping. Leaves flutter in the breeze; they do not flap.


Flap in this case emphasizes an effective motion.

  • A bird flies by flapping its wings.

Flutter hints that something ineffective is happening.

The bird had a broken wing. Try as it might fluttering them, it could not fly.

The site Wikidiff provides an extensive page, What is the difference between flap and flutter? You can often find answers to questions like this simply by typing the two words into a search engine. I typed flap flutter into Google, and that link was listed first.

  • 2
    flutter does not necessarily indicate ineffectiveness. The site you link to specifically has "A bird flutters its wings" as an example. And one wouldn't typically say a butterfly flaps its wings.
    – verbose
    Jan 22 '17 at 2:19
  • @verbose True. I wanted to avoid the dreaded "just a link answer* criticism, but provide enough direct information that was not just a copy of what the other site said. In "A bird flutters its wings.", I do not interpret that to mean it is flying. It brings to my mind a baby bird just moving its wings while still in the nest. For insects and hummingbirds, flutter and fly are indeed directly linked, perhaps because the speed of wing motion is very quick. Still, butterfly flap and fly occurs without seeming awkward.
    – RichF
    Jan 22 '17 at 2:37

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