DARREN: One fell swoop, interesting phrase … Origin?
JACK: It was coined in Macbeth and derives from Middle English.
At one fell swoop means “suddenly, in a single action”. The fell part is an archaic word dating to the 13th century meaning “fierce, savage, cruel, ruthless”; it’s the root of the word felon and has gone out of use except for this one instance.
The phrase was first used, and most probably invented, by William Shakespeare, in his play Macbeth, previously discussed. In the play, it is said by Macduff when he hears that all his family and household have been killed:
All my pretty ones?
Did you say all? O hell-kite! All?
What, all my pretty chickens and their dam
At one fell swoop?
The “kite” that Macduff refers to is the bird of prey, commonly used as a hunting bird in Tudor England. You can see that the “fell swoop” is the swoop of the kite as it quickly descends to catch its prey.
Somehow “at one fell swoop” went from meaning something terrible happening all at once, to just anything happening all at once. Darren uses it to mean good thing happening all at once, but I am unable to disassociate it from its original context, and to me it still suggests some fearsome unexpected blow from above. Maybe I read too much Shakespeare!
Jack’s answer is actually pretty inadequate, or even misleading. It’s not certain that Shakespeare coined it, although it’s likely – he should have said that it first appeared in Macbeth, and that Shakespeare has been credited with coining it. The phrase itself is not Middle English, and presumably he means that the word fell in this example goes back to Middle English.
The Annotated Gilmore Girls 