From a reader…
Father, I recently saw “eundem” in a misallette. My missal uses “eumdem.” I was wondering if these are different cases of the same word (like German den/dem) or if they are just different spellings of the word (or misspellings?).
Eumdem is a legitimate form, though not preferred in the Classical period. The predominate form, even well into Mediaeval Latin, is eundem.
Be mindful that, in classical times, Latin was more “nasal” sounding than it is in our Italian/Roman ecclesiastical pronunciation. Endings with “m” were strongly up in the nose, as it were. This is a reason why endings started to drop off in late Latin and early Italian.
That said, the eundem form is the older, more classical and preferred form. The m of eum at times morphed into an n in the presence of the voiced dental. In post-Classical Latin the m reasserts itself now and then, perhaps because eum is the accusative which is being slammed into the indeclinable suffix –dem.
I find eundem attested first in Ennius, Plautus, etc. I find eumdem attested much less frequently and first in Cicero De legalibus and Celsus De medicina and, after that, in early Christian writers such as Cyprian of Carthage Ad Quirinum and Lactantius De ira Dei. Augustine uses both forms, but I didn’t look to see if he uses the n form in quotations.
I don’t see any pattern of preference.
It could be that there were regional preferences. If could also be that orthography variations and the helpful “corrections” of copyists played a role. Either way, both forms are legit, though eundem is correcter than the other.