General characteristics of the third declension
The third declension includes nouns of all three genders: masculine, feminine, and neuter. In the nominative singular (Nominativus singularis), they have various endings, which makes it difficult to recognize the declension from the dictionary form. However, there is a reliable indicator: for all three genders, the genitive singular (Genetivus singularis) is characterized by the ending -is.
Based on the historical stem, the third declension is divided into three types:
- consonant stem — the stem ends in a consonant (g, c, d, t, b, p, r, l, n, m, s);
- vowel stem — the stem ends in the vowel -i;
- mixed stem — with a mixture of consonant and vowel stem features.
The third consonant declension
The consonant type includes imparisyllabic nouns that have a different number of syllables in Nom. sing. and Gen. sing., with a single consonant preceding the -is ending in the genitive case.
There are no differences in case endings between masculine and feminine nouns. In neuter nouns, Accusativus and Vocativus singularis coincide with Nominativus, and in the plural, these cases end in -a. The cases Dativus and Ablativus pluralis have the same ending -ibus for all three genders.
Examples: victor, victoris — victor; miles, militis — soldier; vox, vocis — voice; nomen, nominis — name.
The third vowel declension
The vowel type includes:
- neuter nouns ending in Nom. sing. in -e (mare, maris — sea), -al (animal, animalis — animal), -ar (exemplar, exemplaris — model);
- feminine parisyllabic nouns having the same number of syllables in Nom. and Gen.: turris — tower, puppis — stern, sitis — thirst, febris — fever, securis — axe;
- parisyllabic nouns denoting names of rivers and cities: Tiberis — Tiber, Neapolis — Naples.
Ending features: in Ablativus singularis — -i, in Genetivus pluralis — -ium. In neuter nouns, in Nom., Acc., Voc. pluralis the ending is -ia (exemplaria, maria). Dative and ablative plural retain the common ending -ibus.
The third mixed declension
The mixed type includes:
- imparisyllabic nouns whose stem ends in two consonants: pars, partis — part; urbs, urbis — city; ars, artis — art;
- parisyllabic nouns ending in Nom. sing. in -is or -es: navis, navis — ship; civis, civis — citizen; nubes, nubis — cloud.
The name "mixed" is due to the fact that Ablativus singularis retains the ending -e (as in the consonant type), while Genetivus pluralis retains the ending -ium (as in the vowel type). Most mixed declension nouns belong to the feminine gender.
Third declension adjectives
Adjectives are declined according to the pattern of the third vowel declension: in Abl. sing. — -i, in Gen. pl. — -ium, in neuter Nom./Acc./Voc. pl. — -ia.
Based on the endings in Nom. sing., adjectives are divided into three groups:
- Adjectives of three endings: m. -er, f. -is, n. -e. Example: alacer, alacris, alacre — lively, energetic.
- Adjectives of two endings: m./f. -is, n. -e. Example: fortis, fortis, forte — strong, brave.
- Adjectives of one ending: the same form for all three genders. Examples: sapiens — wise; felix — happy.
Agreement of adjectives with nouns
An adjective agrees with a noun in gender, number, and case, but retains its own declension. Examples:
- equus alacer — lively horse; puella alacris — lively girl; carmen alacre — lively song;
- vir fortis — brave man; mulier fortis — brave woman; animal forte — brave animal;
- pater felix — happy father; mater felix — happy mother; oppidum felix — happy town.
It is important to remember the accentuation rule: the accent never falls on the last syllable, even if endings are highlighted intonationally for educational purposes.
Key points
- The sign of the third declension is the ending -is in the Genetivus singularis for all three genders.
- The consonant type combines imparisyllabic nouns with a single consonant before -is.
- The vowel type includes neuter nouns in -e, -al, -ar and feminine parisyllabic words.
- The mixed type comprises imparisyllabic words with two consonants in the stem and parisyllabic words in -is/-es; predominantly feminine gender.
- Features of the vowel declension: Abl. sing. -i, Gen. pl. -ium, Nom./Acc. pl. n. -ia.
- Dativus and Ablativus pluralis always end in -ibus.
- Third declension adjectives are declined according to the vowel type and are divided into three groups: three, two, and one ending.
- Agreement between an adjective and a noun occurs in gender, number, and case, but not in declension type.