Doubt about third declension

Question

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?

Answer 1

In masculine and feminine nouns of the third declension, stem-final /n/ is more often than not omitted from the nominative singular form, which will instead end in -ō. In a number of nouns, the oblique stem also contains ō, as it ends in -ōn- (e.g. sermō, oblique stem sermōn-). In others, the oblique stem ends in -in- (e.g. orīgō, oblique stem orīgin-). Carō, carn- is the only one I can think of where the /n/ comes after a consonant in the oblique stem. I’d guess carn- probably originates from syncope of carin-. The different vowel lengths and qualities in the oblique vs nominative stems are from ablaut (complicated by leveling/analogy), followed in Latin by reduction of word-internal short vowels.

This is indeed an unusual area of Latin morphology. The usual way of forming masculine/feminine nominative forms is by the addition of the suffix /s/. I don’t know how the alternative pattern of nominative -ō with oblique -ōn-/-in-/-n- originated.

Wikipedia’s article on Proto-Indo-European declension indicates that the declension pattern with missing /n/ in the nominative singular existed already in PIE (see the “Amphikinetic n-stem” table).

PIE *(s)ker- is the reconstruction of the verbal root that the noun is built on. That verbal root was combined with a suffix to form the word carō/carn-.

Answer 2

This goes back to Proto-Indo-European.

There's a category of nouns in PIE that have *-Cō in the nominative singular and *-Cn-es in the genitive singular. The nominative probably came from something like **-Con-s, with compensatory lengthening, but I'm not sure why the *s is deleted.

The PIE form would then have been something like *kérH-ō (< **kérH-on-s), *kṛH-n-és. Different descendants levelled out this irregularity to different extents; in Latin, the stem was made consistent between the different forms (carō, carnis), but the missing n in the nominative singular was not restored. In Greek, on the other hand, an n present in the stem was generally put into the nominative as well: this is why Latin N-stem nouns tend to end in -ō, -onis, while their Greek equivalents end in -ων, -ωνος.

(This difference was noted even by the ancients, which is why the Latin form of Πλάτων is Platō instead of *Platōn.)