Third Declension: Genitive -is, -um, -ium
-is for one owner, and -um or -ium for several.
How It Works
| Nominative | Genitive singular | Genitive plural |
|---|---|---|
| rex | regis | regum |
| pater | patris | patrum |
| civis | civis | civium |
| urbs | urbis | urbium |
| nox | noctis | noctium |
| corpus | corporis | corporum |
| nomen | nominis | nominum |
A dictionary lists the genitive singular right after the nominative, so it also gives you the stem: reg-, patr-, urb-, noct-, corpor-.
Learn the genitive plural with each noun. The i-stem nouns take -ium, and the entry on i-stem nouns shows how to spot them. A few look like i-stems but take -um: canis has canum, and iuvenis has iuvenum.
The genitive plural -um looks like the singular -um of verbum and servum. The stem and the sentence tell you which one you have.
Examples (5)
- Villa civis magna est.
The citizen's house is big.
Civis is the genitive singular here, "of the citizen".
- Nomen urbis Roma est.
The name of the city is Rome.
Urbis is the genitive singular of urbs.
- Voces civium audio.
I hear the voices of the citizens.
Civium is the genitive plural of civis, an i-stem noun.
- Nomen sacerdotis Paulus est.
The priest's name is Paul.
Sacerdotis is the genitive singular of sacerdos.
- Christus est rex regum.
Christ is the king of kings.
Regum is the genitive plural, "of the kings".
Common Mistakes
Giving a third declension noun the second declension plural ending.
Voces regorum audio.Voces regum audio.Third declension nouns do not take the second declension plural -orum. The genitive plural of rex is regum.
Adding -ium to a noun that is not an i-stem.
Voces regium audio.Voces regum audio.Only i-stem nouns such as civis and urbs take -ium. Rex takes -um: regum.
How It Connects
Learn This First
This is the genitive of the third family, with plural forms to compare.
Related Patterns
Learn Next
Patterns that build on this one.
Words in This Pattern
Practice Third Declension: Genitive -is, -um, -ium in Bubblegum
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