While that’s its meaning in Welsh, it has a specific meaning in English, as a particular type of mountain valley: one bounded on the uphill sides by aretes, IIRC. It may be generic for valley (Cwm Rhondda, for example) in Welsh, but in English the Rhondda Valley is not a cwm; the western flank of Mount Everest, as Brother Cadfael notes, is largely a cwm. (Similarly, there are a lot of geographic loanwords from Spanish which have specific English meanings more particularized than their more generic Spanish meanings.)
I had never heard the word ‘beverage’ spoken aloud until I worked with a Candian who would frequently say things like ‘would you like a beverage?’ ‘I’m just going to get a beverage,’ and ‘I was sitting there drinking a beverage when …’ At first I thought he was doing it ironically, but no, it was just a word he used. I don’t know if it was a Canadian usage or if it was peculiar to him.
I actually thought that ‘shall’ was used in America more than in the UK. I’ve heard it in American movies but hardly ever in real life.
FWIW, I tell my students that, while grammatically ‘shall’ and ‘will’ are identical, ‘will’ includes an element of ‘wanting to’ while shall can be used to talk about permission. This is most easily demonstrated in the negative:
‘You shan’t go to the ball!’ = either you are not going to the ball, or you are not allowed to go to the ball.
‘You won’t go to the ball!’ = you are not going to the ball. ‘You won’t go to the ball?’ can mean either ‘are you not going to the ball?’ or ‘don’t you want to go to the ball?’ (Though the ‘want’ sense is implied, not direct).
If you specifically want to say ‘you are not allowed to go to the ball,’ by using one modal verb, then you have to use ‘shan’t,’ not '‘won’t.’ Or mayn’t, but that’s exremely old-fashioned!
“While not actuallly disgruntled, he was far from being gruntled.”
I use “shall” all the time. I usually use it in this way: “Shall we go to lunch now?” But then, I read a lot of books and I use a lot of words. And I hang out with well-read people.
I nominate “suitor.” Everybody knows what it means and nobody uses it.
I once used the word “extirpate” in a report. Wide spread confusion resulted.
Nobody uses “repetoire” anymore. I mentioned this to my music teacher once and she gave me the oddest look.
I use odd words more often than your average duck 
I’m not sure how universal this is, but it seems to me that (how’s that for waffling on a topic 
) “beverage” is less likely to be misunderstood as meaning something alcoholic than “drink” is (even though a “drink” doesn’t have to be alcoholic).
I used “shall” just last weekend. It was at my nephew’s wedding reception. I held my hand out to my wife and said, “Shall we dance?”
Every time we go to a restaurant, my 12-year-old son asks where the beverage list is.
“Potable” gets used a lot in campgrounds. “Is this potable water?” There are frequently standpipes labeled “potable” and “non-potable” and if one isn’t labeled, you ask.
I rarely hear the word “primer” (as in “tutorial”), and it’s almost always mispronounced when people use it. They tend to say “prime-er” (as in paint) rather than “primm-er.”
When was the last time someone other than me used “elucidate” in conversation?
Maybe when referring to a '50s sitcom. “Ricky Ricardo thinks he has elucidate for the important dinner party, but the scatterbrained redhead is running late and doesn’t meet him until after it’s over.”
Beverage has suffered the indignity of becoming a verb! I heard a flight attendant anounce that “Jenny will be around to beverage you shortly.”
Yikes. Jenny is going to drink me? :eek:
I mostly hear beverage used in ironic terms, such as when Dave Letterman says, “Paul, do you enjoy a lovely beverage?” to fill time, or the slightly cutesy use of the term “adult beverages.”
Note to Jenny: I’m Doug, and I wanna get drunk!
So everyone in Britain mispronounces it? 
(Mind you, primers are more commonly found on lawnmowers than in schoolbags)
I’m giving you music teacher a very odd look right now. Unless she was surprised that any of her students knew the word…
“Why does man kill? He kills for food. And not only food: frequently there must be a beverage.”
Woody Allen
I adore the word “plethora” and use it frequently to make up for most everyone else ignoring it.
Of course, I also like to use the full term “Escherichia coli” instead of the common “E. coli”, but that’s just becaue it’s fun to say.
Beverage is most useful in its written form, as you can deny advocating alcohol consumption when writing about the copious consumption of BEvERages.
I use obfuscate pretty often, and I’m not sure that’s in particularly wide usage currently.
Chimpy
I don’t use that word because I always prefer to eschew obfuscation in my speech.
Back when I waitressed, we used ‘beverages’ fairly often. “Can I get your beverage order for you while you decide?”
I first learned the term hyperlexia when my son’s pre-school teacher pointed out to me that he was the only child who’d ask what the beverage choices were at snack time, as opposed to ‘whadda we got to drink’ I suppose.
I think ‘alas’ is a perfectly wonderful word that’s way under utilized, and I’ll second ‘suitor’ as well.
“Would you say that we had a plethora of pinatas?”