Speaking as someone who has taught a speech synthesizer to vocalize words so that they would be pronounced with more conventional results than default settings produced, I reject your assertion.
I have never in my life heard anyone use the formulation “first from the end.” A penultimate thing is second to last, and an antepenultimate thing is third to last, or third from the end.
How do you pronounce “cwm”? I thought it was said “koom”
Gime? What’s a gime?
Of course nobody ever uses it. It’s just that if you insist on calling something “third from the end” there must logically be a second from the end and a first from the end. The first from the end cannot be the end. It must be one away from the end. Therefore the third from the end cannot be two away from the end; it must be three away from the end. Three away from the end is not the antepenultimate.
Your confusion (you plural) lies in insisting that third to last and three away from the end must be synonymous. They are not.
Some confusion, I think, comes from mixing up “from last” and “to last.” “Second from last” makes more sense for antepenultimate than “second to last.” I did this myself in my first post about this subject.
Also from the fact that many people use “next to last” and “second to last” interchangeably, to mean penultimate. I think we can agree that “next to last” is correct, and “second to last” is probably ambiguous.
Also finally from the desire to make a parallel construction to the other end of the sequence, first, second and third. The parallel to first is last, and then things go wrong. The parallel to second is put as second to last, and then third to last as the parallel for third. (Forgive me here, I just got tired of all the quotation marks.) Unfortunately these parallels don’t really work very well.
What you guys want to say is “third last”. The ultimate is the last (the first last). The penultimate is the second last. The antepenultimate is the third last.
I do like “antepenultimate”. I’ve had the opportunity to use it in a sentence exactly once. It was a glorious moment.
I thought the trivia question that “syzygy” answers is “what word, when written in cursive, has the most consecutive letters below the line.” Five may not be the record any longer but I was told this as a youngster in grade school sixty or so years ago.
This. It has nothing to do with vowels.