Sounds like you've cracked Polly's question Helen.
There is one thing that I kept hearing (not in that programme - I mean on Radio Cmyru in general), and not understanding or finding, and it sounded like
"a fisc" or similar.
The nearest I have found is "ar fysg" (from mysg), meaning "amongst". However, I'm not 100% sure if that's it. I can't quote any context at the moment. I just seem to hear it randomly from time to time.