My old friend Chris Stewart in South Africa wrote recently:
“I do however remember that I was pondering how certain words only survive in phrases (like Kith as in “Kith & Kin”, or Fell as in “Fell Swoop”—or, as the dyslexic community I belong to might say, a “Swell Foop”, which somehow seems to sound like it means something).“
Phrases like “kith and kin” and “to and fro”, in fact, don’t survive. We insist on having current words even in our unpredictable idioms. Most Americans now say “kissin’ kin” and “back and forth” instead of using their archaic counterparts. You meet the archaic phrases only in the written word.
“One fell swoop” is OK because all the words in that phrase are current English words, with or without their original meanings. The important issue seems to be that the components of English phrases, idiomatic or not, be current words in English, whether they make sense in the phrase or not.
The same applies to folk etymology, which I have just explained in the latest addition to Dr. Goodword’s Office and the alphaDictionary resources (click here). Folk etymology converts strange-sounding foreign words into user-friendly English words. The interesting fact is that folk etymology does not care if the words involved make sense so long as they are actual, current English words.
Old French, mousseron, for example, became English mushroom. Mushroom? Mushrooms are not rooms and they have nothing to do with mush? That doesn’t matter to folk etymology so long as mush and room are current English words.