Declension tables

Masculine

pater, patris (m) - father
Case sing. pl.
Nom. pater patres
Acc. patrem patres
Gen. patris patrum
Dat. patri patribus
Abl. patre patribus

Feminine

mater, matris (f) - mother
Case sing. pl.
Nom. mater matres
Acc. matrem matres
Gen. matris matrum
Dat. matri matribus
Abl. matre matribus

Neuter

nomen, nominis (n) - name
Case sing. pl.
Nom. nomen nomina
Acc. nomen nomina
Gen. nominis nominum
Dat. nomini nominibus
Abl. nomine nominibus

The genitive singular will always show the stem change. When looking up third declension words you will find the stem given as: pater, -ris to show the change. It is important to learn both the nominative and the genitive so that you know how the full paradigm will decline.

A variation: i-stems

Some words gain an extra -i- in the genitive plural. These are words that in the nominative have the ending -is, or are only one syllable.

rex, regis (m) - king
Case sing. pl.
Nom. rex reges
Acc. regem reges
Gen. regis regium
Dat. regi regibus
Abl. rege regibus