I was looking at the words in the phrase, “et verbum caro factum est”, and at caro in particular. I am casually interested in Latin (and languages generally) but I do not know it very well. So obviously, I look it up in the dictionary. The table of inflections show us quite a disturbing fact, that the oblique cases and the plurals seem to have some kind of n inserted between the stem and the case marker. Apparently, the same goes for another perfectly ordinary third-declension noun, homo. tigris may optionally have a d inserted which could be related somehow. But it looks as though this does not affect all third declension nouns.
Let’s take the genitive singular. The lemma is caro, so what would we expect? I would have said the genitive singular should be caris. But it’s not; the genitive is carnis. And it will not do to suppose that the epenthesis of n is to satisfy phonotactic constraints, since caris is a presumably attested and perfectly valid word (it may be a conjugation of the verb caro, or an inflection of the adjective, carus). So why is everybody so calm about this?
It should be noted also that the n does not seem to appear in the Proto-Indoeuropean reconstruction, *(s)ker‑ or any other cognates in other languages (including Welsh, ysgar meaning separate; Albanian, harr meaning cut; English, shear, sharp, secateurs, etc. etc.)
Why is there a phantom n turning up in only some forms of caro? Is this related to the same phenomenon in other words like homo, and maybe tigris? Is this same segment found in other Indo-European languages?