One Fell Swoop

Sometimes words turn up in such varied contexts that it is hard to see how they got there.  It almost seems as if they are just wandering around drunk and fell asleep in the wrong bed.

Consider:  "In one fell swoop", a phrase that means "all at once".
Also, fell as a mostly English phrase meaning a hilly upland.
And of course, as a past tense of "fall".  

To take them in order.

A Fell Swoop is not just a rapid action but a cruel or vicious one.  It comes from Medieval Latin fello meaning villain.  See also felon of the same source.  As is so often the case with interesting linguistic coinage, Will Shakespeare gets credit, the first use of the phrase coming in Macbeth. 

"Oh, Hell-Kite! All? What, All my pretty Chickens, and their Damme, At one fell swoope? "

A fell as a geographic feature comes from an unrelated Old German source fels meaning rock.  The sound alike feld and related words like feldspar are not, despite their earthy connotations, related.

Fall, as a verb, is from the bubbling stew of Old English and Proto-German. It's meaning of "to drop from a height, fail, decay or die".  With different roots fell can be the past tense of fall or as a verb, the process of making something fall.  To fell a tree for instance.

Swoop is a peculiar word.  The passage above from Macbeth is a very early use and gives us our sense of it being a blow struck.  But it is said to be a "dialectical survival" of the Old English swapan meaning to "sweep, brandish or dash".  It is said to have knocked around in the odd borderlands between Northern England and lowland Scotland, picking up a couple of "o's" in the process by association with the Norse word "sopa", meaning "to sweep".

So, from sweeping the floors up in the country where rugged fells dominate the landscape we get a Shakespearean phrase generalized from a hawk striking to any sudden evil act.

Words are odd things.