I really don't understand why Spanish reserves the letter 'w' for words acquired from other languages.
5Some time ago we had a lot of fun with ¿Existe un nombre de animal que empiece por la letra “W”?. There we learned that "Hay que tener en cuenta que la letra W no entró a formar parte del alfabeto español hasta hace apenas 50 años"– DiegoApr 28, 2020 at 2:00
The letter ‘W’ wasn’t part of the original latin alphabet. It was the last letter to became part of the Spanish alphabet, the Academy officially recognized it in the 1969 orthography. It was created in the german languages trough the duplication of the latin ‘v’. It was taken as a loanword already in the Middle Ages, to write Germanic words, most of those words now are written with proper Spanish letters like ‘g’ (gualda, güelfo) or ‘v’ (vagón, váter). It is now used in loanwords like web, sándwich, waterpolo, Wagner, Weimar, etc.
The letter doesn't properly belong to the actual spelling of the Spanish language; indeed, it is only normally used to spell out loanwords, especially from gothic languages, German, and English, and Latin language transcriptions for words from oriental languages.
The phoneme /w/ from latin became /v/ in the romance languages; for this reason V ceased to be appropriated to represent the sound /w/ of the Germanic languages.
I guess you could compare it to the letter "ö" from German; the English spelling for this letter becomes "oe", such as in "Schoenberg (Schönberg)", and it's used almost exclusively when spelling out German words.
1Not so sure about the ö/oe similé. AFAIK that is an "accepted alternative spelling" when the original digraph is not available, but I think "the English spelling becomes..." is too strong a statement. Then again, what do I know. :-D Apr 28, 2020 at 12:48
@DevSolar Right, it doesn't fit quite right. It's just that there's no similar thing in English as far as I know– Alex DApr 28, 2020 at 13:57
You mean a letter falling out of use and being replaced? There is đ changing to th... Apr 28, 2020 at 15:23
ö/oe is actually more a case of original orthography developing in differing ways. The umlaut originated as a minuscule 'e' above the affected letter. Some languages (German and Swedish for example) decomposed that into a form resembling a diaresis, while others just shifted it into two letters (and Norwegian did it's own thing and produced 'ø'). English went the way of 'oe' because of French usage derived from Middle Latin orthography for the Greek diphthong 'οι', which was a ligature 'oe' (you can still see this usage in English, for example in 'onomatopoeia'). Apr 28, 2020 at 21:04
If you want a similar case in modern language, I'd suggest looking at the usage of 'l' in Romanized Japanese. It's not found in anything but loanwords, because the Japanese language (rather famously) doesn't have an analog to the sound it makes in most Indo-European languages. Apr 28, 2020 at 21:05