Month names collection / metastudy

[eggyk]

Is the -en a grammatical suffix, so that the uninflected form would be Aberil?

Edit: I see it is supposed to be the genitive of Aberille, sorry I missed that bit. Does it make sense?

The sentence is "Als aberillen wett' vert ir wille" in the original, in 1888 it's "Als abrillen weter vert ir wille". 

Google AI translates it as "Her will changes like april weather", so I suppose its something like "Like april weather goes her will", meaning that it (her will) is unpredictable, or changes quickly like weather in April. 

So, i guess yes it makes sense as the genitive case in that sentence as the weather belongs to/is of April. It actually makes more sense than the months being pluralised.


Edit: Many of the entries on the spreadsheet have this form for many of the months, and haven't been explicitly noted as it's so common. It's really common to see a format like:

mertz
In dem mertzen...
or
von dem mertzen
Der mertz ist..

But this doesn't apply to all of the months equally. Jenner, Hornung, brachmonat, hewmonat, herbstmonat, weinmonat, wintermonat, cristmonat do not follow that pattern afaik. Only mertz, aprille, may, and rarely augst.