What is this linguistic phenomenon?

Good question! There probably isn’t a specific, “official” word for this, but some linguist may have written a paper on it, and gave it a name no one else uses (yet).

“Motor-car” would be another.

Soon, perhaps, “smart-phone.”

I don’t think John McWhorter has discussed this in his “Lexicon Valley” podcast, but maybe he has — it’s just the kind of thing he WOULD discuss.

Let’s not forget fabulous.

Just BTW he left Slate and his podcast is now at Booksmart, although that platform does not seem as readily available in podcast apps.

Thanks! Yup, I follows him there. Gotta click on Booksmart’s “archive” now (at least in my configuration).

Ooh, good one!

Are those all real examples? I mean, were they all originally called by the terms you’re using, and then dropped the modifier? I would have thought that the word ring has always existed independently, for example. It’s not a shortening of finger-ring. Curtains, I’m fairly sure, is not a shortening of window-curtains.

“Heels” is a better example - in the context I assume you mean, anyway. That’s kinda a synechdoche because generally it isn’t just referring to wearing heels that are high, like thick platform heels on biker boots, it’s specifically high and usually dressy, somewhat pointy heels, so the “heels” represent one part of the whole shoe, but we understand that the speaker means something a woman in an evening gown might wear.

Yes.

Yes.

The basic word “ring” meaning some kind of closed circular shape (including the finger-ornament kind of ring) does of course go back a long way. But, as I said, it was modified by compounding it with “finger” to specify a particular type of closed circular shape used as an ornament for the finger. And then the term “finger-ring” lost its modifier, but the more general word “ring” still retained that particular connotation of a finger ornament.

(If you look at the term “finger-ring” in Google Ngram Viewer, you can see how it rapidly climbed in popularity during the 1800s and then gradually declined in the 1900s.)

Of course the more general term “ring” can still be used to mean other things in other contexts, but the point is that it frequently defaults to that more specific meaning. If you hear somebody say “I lost my ring yesterday”, you aren’t going to assume that they lost an arm-ring or a toe-ring or an O-ring or a blackmail ring. You’re going to assume that what they lost is a ring-shaped ornament worn on the finger.

Again, the basic word “curtains” to mean some kind of hanging fabric panel used to screen or enclose something is an old term. But it was modified by compounding it with “window” to specify a particular type of hanging fabric panel used to screen a window. And then the term “window-curtains” lost its modifier, but the more general word “curtains” still retained that particular connotation of a covering for a window.

Unlike the finger-ring, window-curtains weren’t even in use until the past few hundred years. The original function of curtains was to divide rooms or enclose something within a room, like bed-curtains or altar curtains. Windows traditionally might have shutters or carved or paper screens, etc., depending on where you were in the world and in history, but hanging fabric curtains over them is comparatively new.

It seems like the term you are looking for would be the opposite of retronym * but I haven’t found a name for the phenomenon.

* a word that has a modifier added to keep its original meaning, like “bar soap” or “dairy milk”

It’s still not clear to me what you mean. So curtains and ring weren’t the original words; why is it odd that they’re still the original words? Were “finger-ring” and “window-curtain” ever in common use? I’m sure I’d have noticed them in old books if I’d come across them.

I’ve seen window curtains ( without the hyphen) plenty - but possibly only in contexts where door curtains or shower curtains were also being sold.

Google NGrams has many examples.

WHEN a finger ring pinches too tightly, or must be removed in a hurry so that the doctor may treat an injury, the ingenious …

(A finger ring will serve the purpose.) The ring is firmly attached to the loop of string, and you and two other persons pull on different parts of the loop. (See Figs. 3 and 4.) Suddenly the ring drops right off the string

The above authorities do not answer the question involved in this case , which is — Can a gold finger ring designed to contain a watch movement be , as a matter of law , jewelry ?

and catgut string running from ring to trigger to discharge the gun SHOT by a trigger worn as a finger ring , a wrist gun that belches out clouds of tear gas has been designed for the protection of clerks, cashiers and payroll mes

Um, I’m not doubting that the terms have ever been used! Just whether they were common enough that you could say that “curtain” is a shortening of “window curtain.”

Apparently “window curtain” ( no hyphen) was pretty commonly used in the 1920 and 1930s - the following quotes are not from catalogs

As to Exhibit 2 , the defendant contends that it is not a lace window curtain , but merely material , and that this material is net or netting . We find from an examination of the record , including an inspection of the sample …

Q. Did you have a window curtain in the window ? A. Yes , sir . Q. Did that belong to you ? A. Yes , sir ; certainly it belonged to me . Q. What was the price of that ? A. $ 2.50 . 99 Q. Mr. Levine , did you have any lettering on that …

They crossed the room toward the window but as Harry reached out to pull the window curtain aside, the better to watch the storm, he jerked his arm back as though from an electric shock and his elbow found the pit of his chum’s stomach.

He hid his face in the dusty lace window curtain . He looked very small. I could not help remembering how father had said we were to take care of him and not make him cry. Somehow that morning things went ill with the adventure.

Toward the close of the act , thunder is heard and someone draws the window shade while preparations are made for the rain scene , which is seen through the window when the window curtain is raised . This interval was also necessary for …

I’m sorry for being picky, but I’m not sure how some cites existing proves the term was “in common use.” Google ngram seems to think it wasn’t -the red line showing results for “window curtain” barely make it onto the graph:

Can’t check for instances of ring, obviously, because it will always be much more common than finger-ring due to having multiple meanings, not just the jewellery term, so it wouldn’t be a useful comparison. Incidentally, two of the examples for “finger ring” given above weren’t even for the jewellery item either.

“Common use” doesn’t necessarily mean to the exclusion of all other uses - but it’s pretty clear that in the past, “window curtain” was not used exclusively in contexts where there was a need to distinguish between window curtains and door curtains and shower curtains. But the phrase wouldn’t be used today in a sentence that already contained the word window - so at the very least, it didn’t seem odd to be used that way in three of the above quotes. I mean, if someone today asked another person “Did you have a window curtain in the window?” the person being asked would almost certainly think ( and might even say ) “What other sort of curtain would I have in the window?” . Nobody today would say or write

" which is seen through the window when the window curtain is raised"

So it would appear that back then , just mentioning curtains might have resulted in being asked “what kind” - much like at a certain point in my life mentioning a typewriter may have resulted in being asked " manual or electric".

I never said it was. But it does mean that it’s not SO uncommon that it barely charts at all.

The “window curtain is raised” example is because it’s a stage direction from a play, so simply saying “when the curtain is raised” would be extremely confusing. In modern play texts they would, indeed, specify window curtain in that context too.

It’s not because people back then frequently specified which type of curtains they meant, it’s because it’s the text of a stage play.

The first example, also is from a court case, where being extremely specific is commoner than in any other context. If you look at the extract, it’s because the specific description of the item made a difference in customs duty. The second example is the same court case.

So that leaves one example, really. I’m sure there are more than that, but “common use?” Nah.

Yes. As I explained above, “curtain” was a common word for a common object—namely, some kind of drapery dividing or enclosing some part of a space—before curtains were used on windows at all.

So yes, the term “window curtain” came into use at some point after the practice of using curtains on windows came into use, in order to differentiate window curtains from other types of curtains. But nowadays other types of curtains are sufficiently rare that a curtain on a window has become the default meaning of the unmodified term “curtain”, so we don’t use the modified term “window curtain” much anymore.

I’m not trying to claim that the unmodified term “curtain” was never also used to mean a curtain on a window. Nor that the unmodified term “ring” wasn’t also used to mean a ring on a finger.

But my point is that those words also had more general meanings, which is what led to the creation of the (very well attested) terms “finger ring” and “window curtain” to differentiate them from the more general meanings.

And then those modified terms fell out of use, as the thing each of them referred to came to be the unquestioned default meaning of the more general term.

What I want to know is, what’s that called?

Interesting! And yes, clearly a related phenomenon.

Oh, for pity’s sake.

James Joyce, Dubliners:

Lady Barker, The Bedroom and Boudoir:

Gordon Holmes, A Mysterious Disappearance:

James Barrie, Peter Pan:

Percy James Brebner, Christopher Quarles:

There are literally thousands of similar instances. If you haven’t seen a lot of recorded dialogue from the 19th and early 20th centuries, I get why the term “window curtain” might strike you as unfamiliar, but absolutely it was a very commonly used term back in the day.

I also noticed the increase in usage. My personal theory (no evidence to support it) is that it started with Trump’s disregard for the truth and the way his followers have adopted the his strategy of proclaiming obviously false statements. (“My inaugural crowd was the largest in history!”)

That’s not quite gaslighting in the classic definition, but it feels similar in effect. After all, it is a leading cause of Trump Derangement Syndrome, which I know is a term used to mock us liberals but which I think has a grain of truth to it - I freely admit to having suffered TDS.

As more politicians/conservative media personalities followed Trump’s example and presented outrageous claims as simple fact, a term like “gaslight” became more useful because it captured the frustration of those of us who could see through the lies, but were powerless to stop them.

Sez me, anyway.