I have just read an interesting book called ‘Rarebits for Welsh Learners’ by Colin Jones. I have always wondered why so many Welsh nouns are shorter in the plural form than the singular, which seems strange to an English speaker.
This is how Colin explains it.
An ancient Celtic man and his wife were looking into the night sky and saw lots of stars which they called 'sêr’ because it was the group of stars (sêr) they saw first. Then, after a while they noticed that one of the stars was shining brighter than the rest. Sêr un (one star), which over time, sêr un became ‘seren’, one star.
He gives several other examples. Coed, meaning trees. One tree coed un meaning one tree, became coeden
Moch meaning pigs, becomes moch un one pig, and later mochyn.
Fascinating stuff, or at least I thought so. Brilliant little book to add to your collection. I hope Colin doesn’t mind me producing this.