cas bethau - hated things; pethau cas - nasty things
gwahanol bethau - various things; pethau gwahanol - different things
I can’t think of any others…
O, wait: hen ddigon - quite enough, and digon hen - old enough
and diweddar: late/deceased before the noun, and late/recent after the noun, e.g. Y diweddar Siôn Corn, erthyglau diweddar
Yes, that used to get me as well. It can be something that has ended or something that has been renewed.
No! Say it isn’t so! 
Why does cas and gwahanol mutate the following noun? Are they feminine? Benywaidd?
adjectives before a noun always soft mutate that noun, independent of gender or number, but I don’t know why 
Bryn Haul & Haul Fryn
to do with it being a ‘cyfansoddair’ - a compound word … slipped my mind … Diolch 'ta beth!
Ironically cyfansoddair … is a compound word denoting a compound word … oh my brain!
Word of the Day 23/10/2018
(So very sorry for the absence! I was just finishing off the first draft of my novel, sending it off to the publishers and finding my feet again - a very surreal experience, but back on track now. 
)
Tymor = tuh-morr
Yr Hydref = urr hud-rev
Mis Hydref = mees hud-rev
Oer = oyre
Oeri = oyree
Collddail = coll-thaial
Tymor means season
Yr Hydref means the autumn
Mis Hydref means the month of October
Oer means cold
Oeri means to become colder or to make colder
Collddail means deciduous
Sound file -
Some words instantly get one of my favorite “Welsh pronunciation practice songs” to pop up in my head.
In this case, tymer as in “Tymer Aspirin”
I haven’t spent much figuring out the translations yet, but from my understanding he (the author) likes to play with the sound of words and different meanings a bit in and out of strict logic. Am I right?
Ac mae hyn i gyd fel tymer aspirin,
Nofio’n noeth mewn tymer trwm.
Deg gwaith yn waeth na gwanwyn,
Ychydig well na’r bywyd llwm
Oh wonderful word for deciduous! Lose leaves
My Daughter had a biology test last week and deciduous was one of the answers. Now all I need is the verb ‘to rake’ to add it to the collddail dail I’ll be raking. 
Ah, Hydref!
Collddail is one of those words like llaeth and llyfr that remind the Italian word (in this case “caduco”) more than the English one.
Then you hear how they sound and 
…oh well, not so much!
Dail doesn’t even look like foglia, nor leaf though!
But foglia sounds like foliage.
I love collddail too. It is so straightforward and descriptive.
Sue
I think someone from this account is watching this thread.
Oh! I wonder what the trees were called before the 1950s. I tried looking in a few online dictionaries, but they gave collddail.
Sue
My Y Geiriadur Mawr also gives deilgoll for deciduous. Perhaps the two words were in competition at one time?
Or the same compound word in reverse order? Lose leaves. Thats easier than English 
Or “losing leaves” vs “leaf lost” - I rather like the latter, though it is not the “accepted” word. Seems a little easier for me to pronounce. (That ll right next to the dd is tricky!)
There was someting similat on the FB Britonnic word of the day for Skull.
Ill probably get these wrong, but I think the Welsh was something like penglog. Cornish and Breton wrre something like klopenn