What's the origin of "one fell swoop"?
Dear Straight Dope:
My late grandmother often used the phrase "one fell swoop" to indicate doing many things at once. What is a fell swoop? And how did this phrase get into our everyday vernacular?
Fell, from Old English, means awful, terrible or horrible. The word's stem can also be seen in "felon," which now is mostly used to mean someone who has been convicted of a felony (a serious crime), but which formerly meant one who is terrible, horrible or awful in behavior. The "swoop" is an onomotopoeia, indicating a fast movement. All together, "one fell swoop" means a swift, horrible blow.
Shakespeare, originator of so many English catchphrases, may have dreamed up this one too. It appears in "Macbeth": "What! all my pretty chickens and their dam/At one fell swoop?" (act IV, scene 3) laments Macduff, upon learning his wife and children have been killed by Macbeth. This appears to be the earliest recorded use of the phrase, although it may have been in common usage before Shakespeare wrote it down.
It's interesting that "one fell swoop," which originally had such a dire connotation, is now a mild term meaning "all at once." A similar fate has befallen the expression "fey charm." Few people know that "fey" is an old Scottish term meaning (a) fated to die soon, or (b) full of the sense of approaching death (these definitions from the American Heritage Dictionary). So if you say someone has a certain fey charm, you're saying he or she exerts that morbid fascination associated with imminent death.