In the eleventh class of the Latin from Scratch course, we’ll study the third declension, the most complex but probably the most prolific. That’s why it is so important to master it already. Also, what we’re about to learn now will be necessary for the 3rd declension adjectives.
Contents
I explain everything in the following video (⏳ 18m 06s ⌛):
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Morphology of the third declension
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The third declension is divided into two big groups. We can quickly classify a 3rd declension noun by looking at the statement:
- consonant-stem: nouns with a different amount of syllables between the nominative and the genitive (e.g. mi‑les, mi‑li‑tis)
- i-stem: nouns with the same amount of syllables (e.g. ci‑vis, ci‑vis)
However, there are exceptions where the rules are the opposite:
- consonant-stem (but look like i-stem): mater, matris; frater, fratris; pater, patris
- i-stem (but look like consonant-stem): nouns whose nominative singular ends in 2 or more consonants and whose genitive singular has 2 consonants right before ‑is (e.g. mons, montis; urbs, urbis; pars, partis)
The distinction between these two groups is relatively important, since there are some different endings.
Consonant-stem
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Masculine and feminine nouns are declined the same, whereas neuter nouns have some already known particularities.
Precisely because of these particularities, it is important to quickly identify neuter nouns, which meet one of the following criteria:
- nominative singular in ‑men (e.g. carmen, carminis; flumen, fluminis)
- nominative singular in ‑us and genitive singular in ‑eris, ‑oris or ‑uris (e.g. vulnus, vulneris; corpus, corporis; ius, iuris); not to be confused with 2nd or 4th declension nouns, which can also end in ‑us!
- dental-stem (d, t) with a nominative not ending in ‑s (e.g. caput, capitis; cor, cordis; lac, lactis)
In the following four tables, you have to take into account that the nominative and vocative (and accusative neuter) singular do not have an ending of their own; instead, each specific word has its own ending for those cases.
Masculine-feminine declension
| nom. sg. | homo | nom. pl. | hominēs |
| voc. sg. | homo | voc. pl. | hominēs |
| ac. sg. | hominĕm | ac. pl. | hominēs |
| gen. sg. | hominĭs | gen. pl. | hominŭm |
| dat. sg. | hominī | dat. pl. | hominĭbus |
| ab. sg. | hominĕ | ab. pl. | hominĭbus |
Neuter declension
| nom. sg. | caput | nom. pl. | capită |
| voc. sg. | caput | voc. pl. | capită |
| ac. sg. | caput | ac. pl. | capită |
| gen. sg. | capitĭs | gen. pl. | capitŭm |
| dat. sg. | capitī | dat. pl. | capitĭbus |
| ab. sg. | capitĕ | ab. pl. | capitĭbus |
i-stem
The i-stem declension is not so common in nouns, but it is widely used in adjectives. By the way, you can think of it as “the irregular ones” (as opposed to consonant-stem, which are “the regular ones”).
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Also this group has masculine-feminine and neuter paradigms. To find out what nouns are neuter, we should look at the nominative singular: they end in ‑e (e.g. mare, maris; rete, retis). However, many of them have lost this ‑e, which makes them look like consonant-stem; we know they are i-stem because the nominative ends in ‑al or ‑ar, as long as they don’t refer to persons (e.g. animal, animalis; vectigal, vectigalis; exemplar, exemplaris).
Masculine-feminine declension
| nom. sg. | hostis | nom. pl. | hostēs |
| voc. sg. | hostis | voc. pl. | hostēs |
| ac. sg. | hostĕm | ac. pl. | hostēs (-is) |
| gen. sg. | hostĭs | gen. pl. | hostiŭm |
| dat. sg. | hostī | dat. pl. | hostĭbus |
| ab. sg. | hostĕ | ab. pl. | hostĭbus |
The accusative plural is most often ‑ēs, but it can appear as ‑is.
Neuter declension
| nom. sg. | mare | nom. pl. | mariă |
| voc. sg. | mare | voc. pl. | mariă |
| ac. sg. | mare | ac. pl. | mariă |
| gen. sg. | marĭs | gen. pl. | mariŭm |
| dat. sg. | marī | dat. pl. | marĭbus |
| ab. sg. | marī | ab. pl. | marĭbus |
That’s most of the theory we need to know about the third declension. Now let’s learn its adjectives.
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Wiktionary lists that the ablative singular of “mare” is “marī” with the long ending -ī https://en.wiktionary.org/wiki/mare#Latin I’ve also seen this in other sources. However, here it is listed with a short ending -ĭ. So I’m wondering which one it is?
Yes, precisely in that link you can see “The ablative singular can be marī or mare.”
The thing with i-stem nouns is that they are “the irregular ones” (as opposed to consonant-stem, which are “the regular ones”), so they tend to copy features from consonant-stem nouns.
So in theory you should have marī, but you can also find mare (and the same with many other i-stem nouns).
My honest advice is to not obsess over this and just be aware that you can have both.
Thanks for your reply!
Yes, it is listed as both “marī” or “mare” in Wiktionary, but not as “mari” like it’s listed here (or “marĭ” to be more precise). So that’s what got me confused.
But I’ll take your advice and won’t dwell on it.
It’s good to know that the i-stem nouns are the “irregular ones”. If I can give an improvement idea, I think it might be nice to mention that in the text also.
Ah, yes, typo! Thanks!