FAM: Lesson - Declining Cardinal Numbers
Declining Cardinal Numbers
Only three of the cardinal numbers are fully declined: unus, duo, tres. The cardinal number mille (1000), has a related noun form which can be declined: milia, milium, n. pl - thousands. All the remaining cardinal numbers do not decline (the term for an adjective or noun that cannot be declined is indeclinable). Study the declension charts for unus, duo, tres and mille below.
Unus
Only uses singular forms; note the genitive (-ius) and dative (-i) forms (the pattern you see for unus is used for all irregular adjectives).
| Case | Masculine | Feminine | Neuter |
|---|---|---|---|
| Nominative | unus | una | unum |
| Genitive | unius | unius | unius |
| Dative | uni | uni | uni |
| Accusative | unum | unam | unum |
| Ablative | uno | una | uno |
| Vocative | une | una | unum |
Duo
Only uses plural forms; note the irregular looking dative and ablative forms. We have actually seen the ending -abus before: 1st declension nouns like filia or dea, which use the same noun base as a 2nd declension masculine noun (filius, deus) use -abus for the dative and ablative plural to distinguish it from the masculine -is (filiabus vs. filiis). The ending -obus is just a masculine/neuter version of -abus, used exclusively for the adjective duo.
| Case | Masculine | Feminine | Neuter |
|---|---|---|---|
| Nominative | duo | duae | duo |
| Genitive | duorum | duarum | duorum |
| Dative | duobus | duabus | duobus |
| Accusative | duos | duas | duo |
| Ablative | duobus | duabus | duobus |
| Vocative | duo | duae | duo |
Tres
Only uses plural forms; declined following 3rd declension i-stem rules. Note that the masculine and feminine forms are identical, so the dictionary entry is often written: tres, tria - three. Here, we will expand it to show all three genders, for clarity.
| Case | Masculine | Feminine | Neuter |
|---|---|---|---|
| Nominative | tres | tres | tria |
| Genitive | trium | trium | trium |
| Dative | tribus | tribus | tribus |
| Accusative | tres | tres | tria |
| Ablative | tribus | tribus | tribus |
| Vocative | tres | tres | tria |
Mille
The number 1000 is indeclinable (is not declined) as an adjective, but has a declinable noun form, which uses neuter plural, 3rd declension i-stem forms:
| Case | Adjective | Plural Noun | Noun Meaning |
|---|---|---|---|
| Nominative | mille | milia | Thousands... |
| Genitive | mille | milium | of thousands |
| Dative | mille | milibus | to/for thousands |
| Accusative | mille | milia | ...thousands |
| Ablative | mille | milibus | by/with/from thousands |
| Vocative | mille | milia | thousands (being addressed) |