2190: Plural as the Default Dec 13, 2020

Usually, plurals are formed from the singular, but this is not always the case. Exceptionally, in Welsh for instance there are words for which the plural is the base and singulars are formed off of that. This is on top of the fact Welsh has plurals where no non-affixed form exists: ‘merlen’ (a pony) and ‘merlod’ (ponies), but no *merl. Now, take the examples of

Llygod (mice, pl.) but llygoden (mouse, sg.)

Erfin (turnips, pl.) but erfinen (turnip sg.)

These have the same singular ending as with ‘merlen’ but the plural form is indistinguishable from a root, lacking any additional morphology. Keep in mind this is unlike languages like Latin or Finnish where endings indicate not only singular–plural, but also case. There is no particular reason why the singular will resemble the root if one would have to, but looking at how exceptional this is, it could be said to make intuitive sense. Celtic languages did once historically have cases which one could try to explain this with, but so did English, French, and many other such Indo-European languages where this does not happen.