Most today's English speakers probably don't pay any thought to the possible German root, a word that meant 'spear,' meaning a pointed stick to skewer the meat with. Most will think spareribs refers to how the butcher left meat on the bones.
If the German root was true, then 'spareribs,' by how it is pronounced, had given rise to a misunderstand that is also perfectly sensible, and that ends up with the same meaning anyway.
Are there many words that had undergone that kind of good misunderstanding? Enough of that phenomenon to have a word for?
Probably tons of 'em, but by definition we've forgotten most.
The only ones that occur to me immediately, though, are not bona fide words but idioms. For example, I imagine modern youngsters would assume that we "boot" a computer as a sort of jocular image of kicking something because it isn't working right. But I was around when it was still called "bootstrapping" the computer—shortening it to "boot" came later—which tells me that it was originally a reference to "raising yourself by your own bootstraps". I can explain why that makes sense, if you want, but I expect most of us here already know so I'll spare you unless asked.
And we've all heard malaprops that set our teeth on edge. It makes perfect sense to me that someone should believe in "taking another tact" if the first attempt didn't succeed—perfect sense, but it's wrong.
But you have actual words in mind, not mistaken idioms. It seems to me I just posted one recently, some word that obviously was from.... Ah, I remember, and I don't think I posted it here, it was in an email to my mother: I realized, only a month or three ago, that "gull" and "guile" must be related. Obviously.
But no; when I looked it up, it turned out that "gull" is an old Germanic word (Old Norse, maybe) and has referred to sea birds since time out of mind but came to refer to gullibility only in the 1500s, whereas "guile" comes from Latin. The relationship in their meanings is sheer coincidence. Not exactly the same thing as your question, but close, I think.
Bob Bridges said
I imagine modern youngsters would assume that we "boot" a computer as a sort of jocular image of kicking something because it isn't working right. But I was around when it was still called "bootstrapping" the computer—shortening it to "boot" came later—which tells me that it was originally a reference to "raising yourself by your own bootstraps". I can explain why that makes sense, if you want, but I expect most of us here already know so I'll spare you unless asked.
You want to see a real shift in idiom, ask someone under 25 to explain the expression "to sound like a broken record". Or ask them what "cc:" at the top of an e-mail stands for.
I realized, only a month or three ago, that "gull" and "guile" must be related. Obviously.
But no; when I looked it up, it turned out that "gull" is an old Germanic word (Old Norse, maybe) and has referred to sea birds since time out of mind but came to refer to gullibility only in the 1500s, whereas "guile" comes from Latin. The relationship in their meanings is sheer coincidence.
I made a similar assumption for years about "filet" and "flay". It was obvious to me that one came from the other, since they both refer to stripping away layers of skin. The misconception stood until someone pointed out that the British say "fillet" like "fill it", which bears virtually no resemblance to "flay".
You might as well ask a kid why we talk of "dialing" a number or "tape" a performance.
"Floppy disc". "Platter" (of a vinyl record). "Sounding like a broken record", as someone here cited in another thread. Or "two bits" for that matter.
Here's one I never thought of before: the shared meaning of both "throttle" and "choke" in an internal-combustion engine. Maybe that was before my time, or at least before I was paying attention. I always thought the throttle was what I would nowadays call the accelerator; but now I notice that its basic meaning is just the opposite. Does this have to do with the way an accelerator actually works...or perhaps did work?