This morning I was relatively lucky when I was looking up "llewys" ..... and it wasn't there. I guessed it was probably a peculiar plural, and fortunately the context gave it away ... whatever it/they were, they were being pushed up someone's ( wait for it) ... arms ! Not what you thought ! So I made a wild guess and looked up what a sleeve was ... and bingo ... t'was llawes ! ..... llawes ► llewys ... the little devils.
Had the "llewys" thing been getting pushed up someone's nose instead, it would have been a lot trickier. Or someone's chimney. Or their trousers. Tricky.
But many a time the context isn't helpful at all and you're totally stuck. So, any "patterns" that might lead you to the singular version must be good ...
Well now, you get a lot of that a ► e business with peculiar plurals ... it's worth remembering, so here's a few examples for your enjoyment and education .. so when you come across an e-word it might really be an "a" in the singular. Read on ....
PLURAL SINGULAR
meysydd ...... maes
ceilliau caill
meibion mab
mecryll macreth
meinion main
meinciau mainc
methion maith
menig maneg
elltydd allt
meirw marw
meirch march
erydr aradr
eraill arall
eirch arch
eirth arth
esgyll asgell
cleisiau clais
heuliau haul
There's a bit of an ei ► ai sub-pattern in there ... here's some more ..
heiddiau haidd
heintiau haint
heigiau haig
geiriau gair
ffeithiau ffaith
ceiliau cail
ceibiau caib
ceilliau caill
.... as you can see, they aren't hard to find !
Ages ago I started a list of all these peculiar plurals but it's just too big a task .... the truth is, any ½-decent dictionary-maker should either put the plural versions in with the alphabetical sequence, or, more realistically, put the more common ones in a separate list somewhere. You know it makes sense.
But now, here's Colorama and "Mynydd Hud" ...