Ah, not sure whether this is coincidence or not, jheem, but I'd been interested in a long time before coming to AWAD in the long-time-ago dictates that the vowels were 'a, e, i, o, u and sometimes y and w.'

As a child I could easily figure out the first six, but the 'w' threw me for years until finding 'cwm' in an American Heritage dictionary, and voila! There was that 'w' sounding like a 'u.' In fact, I was very curious about other 'w' words in the language after having found still another in American Heritage: crwth. So I came to this place a little over two years ago and posed my question about 'w' vowell words beyond cwm and crwth. Well, the answers came in. I believe Maverick may have been the one who provided a very long list of 'w' as vowell words, quite impressive.

Now to learn from you that even 'y' had possessed some sort of 'u' sounds is even more intesting--and the connections, both practical and metaphorical, abound: The empyreal itself--and the thought of the purest realm as being the sky itself--and not so pure today because of how we pollute it with our advance forward (or is it backward?). Pyres and purification, when pyres actually are polluting. There's a metaphysical kind of fiery purity, and then there's the impurity of actual fires.

"Y" has gained quite more signficance in my way of thinking, so I thank you very much for your most valuable instruction here on this thread. I'm sure others are as very interested in what you've provided.

Addendum: Here's mav's list from years gone by of the 'w' words, for anyone who's interested. I saved the list intentionally along with his comments--Mav', I'm 99% sure it was you who wrote what follows!:

"dwr = water
swn = sound

those two should have a 'to' or roof over the 'w' - like this letter's: û - but I can't seem to find that in the standard character sets...)

ffrwd = misty, damp (I think)
twr = tower
twll = hole
bwlch = gap (in hills etc), pass
hwn = that
pwll = pool
drws = door
drwg = bad or naughty
drwm = drum
dwbl = double
gwrth = counter or contra
gwr = man (and interestingly gwrach = witch!)
lwc = luck
llwgr = corruption
dwl = dull, stupid
dwndwr = hubub, babble [ dwndwrdoondoor]
dwthwn = day (tho around here we woud use dydd)
llwnc = gulp, swallow
dwrn = fist, handle, hilt
llwm = bare, destitute
mwrthwt = hammer
cwrw - BEER!
wydd = goose (I think this is a soft mutation of gwydd)
cwn = dog or dogs (depending on where in Wales)
cwl = cool, wicked (modern transliteration)
cwrwgl = coracle (traditional withy & skin fishing boat)
mwlwg mwlwg
mwlwg = refuse, sweepings
mwng - mane (horse's)
pwt = short ('Gog' or North Welsh)
cwcw = cuckoo
cwpl = couple; tie-beam
cwmwl = cloud
cwt is one that I like since it has quite varied meanings depending on context: tail, skirt, queue, hut, sty - the common feature seems to be something as an appendage.
cwr = edge, border or skirt, whereas cwrs = course
mwrllwch = fog, mist, vapour (another Gog term, my kids said) and one for Dr Bill (YCLIU!): cwthwm"