4th or u- Declension

[AureliaeLacrimae]

3rd declension is a varied one, so I'm going to leave it for the time being. That's why I immediately skipped forward to 4th or u-declension and later on to 5th or e-declension.

4th or u-Declension

Nominative singular always ends on either -us (masculine nouns) or -u (neuter), and the base always ends on -u. There are only seven of feminine nouns in this declension and they follow masculine endings. The only difference is the form of adjective - they take feminine adjective.

                Sg                                                          Pl

N      fructus            genu                          fructus        genua

G      fructus            genus                        fructuum      genuum

D      fructui            genui                        fructibus        genibus

Acc    fructum          genu                          fructus          genua

V      fructus            genu                          fructus          genua

Ab    fructu              genu                          fructibus        genibus

Remember the rule of the neuter? It's followed here as well!

Reminder:

All neuter nouns have the same form for Nominative, Accusative, and Vocative. Also, in plural, these three end in -a!

There are several exceptions to D and Ab plural form. I'll name them here. The reason: to differ from the nouns which belong to 3rd declension and have the same -ibus ending, but about that more later:

                                    Dative/Ablative plural form

acus, acus, f - needle        - acubus  (instead of acibus)

arcus, arcus, m - arch      - arcubus (instead of arcibus)

lacus, lacus, m - lake        - lacubus (instead of lacibus)

quercus, quercus, f - oak  - quercubus (instead of quercibus)

specus, specus, m - cave  - specubus (instead of specibus)

artus, artus, m - extremity - artubus (instead of artibus)

partus, partus, m - birth    - partubus (instead of partibus)

Feminine nouns:

Idus, us, f - 15th day of the month    Idus Martiae - 15th of March

porticus, us, f - porch                    porticus alta - high porch

acus, us, f - needle                        acus acuta - sharp needle

manus, us, f - hand                        manus valida - strong hand

domus, us, f - home                      domus antiqua - old house

quercus, us, f - oak                        quercus umbrosa - shadowy oak

domus, us, f is the only noun which follows an exception!!

This is how you decline domus:

            Singular                      Plural

N          domus                      domus

G          domus                      domuum/domorum!!!

D          domui                      domibus

Acc        domum                      domos!!!

V          domus                      domus

Ab          domo!!                      domibus

Wherever you see exclamation marks, that's where you have to note the change. Domus is a noun which had taken half of the second declension. Ablative sg, Accusative Plural and optional G plural are from the second declension. The rest follows the pattern of fourth.