In the fifteenth class of the Latin from Scratch course, we’ll study the fourth declension. The first, second and third declensions are the most common ones, but we will find some frequent nouns in this fourth declension, which by the way shouldn’t be confused with the second declension.
I explain everything in the following video ():
Morphology of the fourth declension
In the fourth declension we will find two groups, clearly differentiated by the statement:
- nominative singular ‑us (masculine and feminine)
- nominative singular ‑u (neuter)
They’re pretty much the same, but with the already familiar differences in the neuter nouns.
Nominative ending in ‑us
Masculine and feminine nouns in the fourth declension are declined exactly the same. The only way to know if a noun is masculine or feminine is by looking it up in the dictionary.
|nom. sg.||exercitŭs||nom. pl.||exercitūs|
|voc. sg.||exercitŭs||voc. pl.||exercitūs|
|ac. sg.||exercitŭm||ac. pl.||exercitūs|
|gen. sg.||exercitūs||gen. pl.||exercitŭŭm|
|dat. sg.||exercitŭī||dat. pl.||exercitĭbŭs|
|ab. sg.||exercitū||ab. pl.||exercitĭbŭs|
In some words, mostly disyllabic, with nominative singular in ‑cus, we will often find their dative-ablative plural in ‑ubus instead of ‑ibus (e.g. arcus, ‑us: arcibus → arcubus to distinguish it from arcibus ← arx, arcis).
Nominative ending in ‑u
Neuter nouns in the fourth declension have the same special features we find in neuter nouns of other declensions: same nominative-vocative-accusative, and plural in ‑a. We know a noun is neuter because of the first form of the statement.
|nom. sg.||cornū||nom. pl.||cornŭă|
|voc. sg.||cornū||voc. pl.||cornŭă|
|ac. sg.||cornū||ac. pl.||cornŭă|
|gen. sg.||cornūs||gen. pl.||cornŭŭm|
|dat. sg.||cornŭī||dat. pl.||cornĭbŭs|
|ab. sg.||cornū||ab. pl.||cornĭbŭs|
And that’s everything you need to know about the fourth declension. Now let’s study the last one: the fifth declension!