Third Declension: rex, regis
Look at the genitive: it ends in -is, and what comes before -is is the stem.
How It Works
The noun rex is the model. Its stem is reg-, which you can see in every form except the nominative.
| Case | Singular | Plural |
|---|---|---|
| nominative | rex | reges |
| genitive | regis | regum |
| dative | regi | regibus |
| accusative | regem | reges |
| ablative | rege | regibus |
The nominative rex hides the stem, so always check the genitive. Pater has the stem patr-, urbs has urb- and corpus has corpor-.
Some nouns of this family have small differences: neuter nouns, and the i-stem nouns such as civis and urbs. Each has its own entry. A dictionary also gives the gender, so learn it together with the noun.
Examples (5)
- Rex urbem videt.
The king sees the city.
Rex is the nominative, and urbem is the accusative.
- Filius regis in villa habitat.
The king's son lives in the house.
Regis is the genitive of rex.
- Iulia patri rosam dat.
Iulia gives a rose to her father.
Patri is the dative of pater.
- Cives regem laudant.
The citizens praise the king.
Cives is the nominative plural, and regem is the accusative singular.
- Sacerdos missam celebrat.
The priest celebrates Mass.
Sacerdos is a third declension noun; its genitive is sacerdotis.
Common Mistakes
Building the accusative from the nominative.
Marcus rexem videt.Marcus regem videt.The nominative rex hides the stem. Look at the genitive, regis, take off -is to get reg-, and add -em: regem.
How It Connects
Learn This First
The third family has its own endings, so the dictionary forms, the cases and the accusative plural come first.
- Dictionary Forms of Nouns
Know the dictionary forms of nouns, because the genitive shows the stem: rex, regis.
Foundations - Accusative Plural: -as, -os, -aAccusative Plural Endings
Know -as, -os and -a, because the third family has new endings for the same jobs: reges beside puellas and servos.
Level 2 - The Ablative Case
Know the cases up to the ablative, because rex is shown in every one of them: rex, regis, regi, regem, rege.
Level 2
Related Patterns
Learn Next
Patterns that build on this one.
Words in This Pattern
Practice Third Declension: rex, regis in Bubblegum
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