Classical Languages - Latin - Morphology - Nouns - Third Declension

Nouns
Third Declension

Third Declension

Prerequisites: Nouns, First and Second Declensions

Next: Fourth and Fifth Declensions, Irregular and Defective Nouns

The third declension is the largest and the most varied of the five. It contains nouns of all three genders, with nominatives in many different shapes, and it combines two historically separate groups of nouns, the consonant stems and the i-stems, whose endings have partly merged. Because the nominative rarely reveals the stem, the genitive singular must be learned with every noun. This page gives the endings, the rules for telling the two groups apart, the gender patterns and the principal types. The full tables are in Paradigms: nouns.

Identification

  • Genitive singular -is.
  • Stem: remove -is from the genitive: rēx, rēgis gives the stem rēg-; corpus, corporis gives corpor-.
  • Nominative: no single pattern. It may be the stem alone (cōnsul, pater), the stem with -s (rēx, urbs), or a changed form (homō, hominis, nōmen, nōminis, corpus, corporis).
  • Gender: masculine, feminine or neuter. It must be learned with the noun, though several patterns help (see below).

Endings

Masculine and feminine

Case Singular Plural
Nominative various -ēs
Genitive -is -um (i-stems -ium)
Dative -ī -ibus
Accusative -em -ēs
Ablative -e (some i-stems -ī) -ibus
Vocative same as nominative -ēs

Neuter

Case Singular Plural
Nominative various -a (i-stems -ia)
Genitive -is -um (i-stems -ium)
Dative -ī -ibus
Accusative same as nominative -a (i-stems -ia)
Ablative -e (i-stems -ī) -ibus
Vocative same as nominative -a (i-stems -ia)

The neuter keeps the three neuter rules: nominative and accusative identical, plural in -a, vocative equal to the nominative.

Notes

  1. The ending -ibus replaces the -īs of the first two declensions: dative and ablative plural are always -ibus here.
  2. The accusative singular is -em for masculine and feminine: it ends in -m, as in every declension.
  3. The ending -a of the neuter plural looks like the first declension singular, so check the gender: nōmina is a neuter plural, rosa a feminine singular.
  4. The vowel length of the plural -ēs is long, as is the ī of the dative singular.

Two groups: consonant stems and i-stems

The two groups share most endings and differ in only a few places. The i-stems have:

Feature Consonant stems i-stems
Genitive plural -um: rēgum -ium: cīvium
Accusative plural (older texts) -ēs -ēs or -īs
Neuter ablative singular -e: corpore -ī: marī
Neuter nominative and accusative plural -a: corpora -ia: maria

Other forms are the same in both groups. Remember too that a few masculine and feminine i-stems have the ablative singular in -ī, the accusative singular in -im, or both, as the exceptions below show.

How to recognise an i-stem

The dictionary gives only the nominative and the genitive singular, so the group is identified by these rules:

  1. Parisyllabic nouns in -is and -ēs: nouns with the same number of syllables in the nominative and the genitive singular are i-stems: cīvis, cīvis; hostis, hostis; avis, avis; nūbēs, nūbis; nāvis, nāvis. Exceptions with genitive plural in -um: canis (dog), iuvenis (young man) and a few others.
  2. Monosyllables in -s or -x preceded by a consonant: urbs, urbis; mōns, montis; pars, partis; gēns, gentis; dēns, dentis; mors, mortis; ars, artis; arx, arcis. nox, noctis also belongs to this group.
  3. Neuters in -e, -al, -ar: mare, maris; animal, animālis; exemplar, exemplāris. These also have the ablative singular in -ī.
  4. Plural-only nouns such as moenia (walls), moenium.

Everything else is a consonant stem. When in doubt, check the genitive plural in Lewis and Short.

Consonant stems

Consonant stems are classified by the final consonant of the stem, which shows in the genitive:

Stem ends in Nominative Genitive Examples
guttural (c, g) -x (= c or g + s) -cis, -gis rēx, rēgis; dux, ducis; lēx, lēgis; vōx, vōcis; pāx, pācis
dental (t, d) -s (the dental drops out) -tis, -dis mīles, mīlitis; pēs, pedis; virtūs, virtūtis; aetās, aetātis; laus, laudis
labial (p, b) -ps -pis prīnceps, prīncipis
liquid (l, r) stem alone, or -or -lis, -ris cōnsul, cōnsulis; pater, patris; māter, mātris; honor, honōris
nasal (n, m) -ō, -en, -s -inis, -onis, -minis homō, hominis; leō, leōnis; nōmen, nōminis; hiems, hiemis
s-stem -us, -or, -ōs -eris, -oris, -ōris corpus, corporis; genus, generis; tempus, temporis; mōs, mōris; flōs, flōris

Sound changes

  • Guttural + s gives x: rēg-s becomes rēx.
  • A dental before -s is lost: mīlit-s becomes mīles (the vowel changes too); ped-s becomes pēs.
  • Rhotacism in s-stems: an original s between vowels became r. The stem of corpus was originally corpos-, and it became corpor- before the endings. The nominative honor replaced the older honōs by analogy with the other cases.
  • Vowel changes in the stem: homō, hominis; nōmen, nōminis. The stem vowel i appears in all cases except the nominative.

Gender patterns

The gender of third declension nouns is partly predictable from the nominative ending. The rules are approximate, and every group has exceptions, so the gender is always learned with the noun.

Masculine

Ending Examples
-or honor, amor, labor, ōrātor, timor
-ōs mōs, flōs
-er pater, frāter
-ex rēx, grex
-ō (gen. -ōnis) leō, sermō
-ēs (gen. -itis) mīles, eques, comes

Feminine

Ending Examples
-ās (gen. -ātis) aetās, cīvitās
-tūs, -tūdō virtūs, multitūdō
-tiō, -siō nātiō, ōrātiō
-dō, -gō virgō, imāgō
-x lēx, pāx, vōx, nox (but rēx, grex and dux are masculine)
-s after a consonant urbs, pars, mors, ars, gēns (but mōns is masculine)
-is nāvis, avis
māter māter

Neuter

Ending Examples
-men nōmen, flūmen, carmen
-us (gen. -eris, -oris) genus, corpus, tempus, opus
-e, -al, -ar mare, animal, exemplar
others caput, capitis, cor, cordis, lac, lactis

Both genders

cīvis (citizen), hostis (enemy), canis (dog), comes (companion) and others can be masculine or feminine, depending on the person: the gender follows the meaning.

Models

Consonant stems: rēx, rēgis m. king, and homō, hominis m. man.

Case rēx sing. pl. homō sing. pl.
Nom. rēx rēgēs homō hominēs
Gen. rēgis rēgum hominis hominum
Dat. rēgī rēgibus hominī hominibus
Acc. rēgem rēgēs hominem hominēs
Abl. rēge rēgibus homine hominibus
Voc. rēx rēgēs homō hominēs

Neuter consonant stems: nōmen, nōminis n. name, and corpus, corporis n. body.

Case nōmen sing. pl. corpus sing. pl.
Nom. nōmen nōmina corpus corpora
Gen. nōminis nōminum corporis corporum
Dat. nōminī nōminibus corporī corporibus
Acc. nōmen nōmina corpus corpora
Abl. nōmine nōminibus corpore corporibus
Voc. nōmen nōmina corpus corpora

I-stems: cīvis, cīvis m./f. citizen, and urbs, urbis f. city.

Case cīvis sing. pl. urbs sing. pl.
Nom. cīvis cīvēs urbs urbēs
Gen. cīvis cīvium urbis urbium
Dat. cīvī cīvibus urbī urbibus
Acc. cīvem cīvēs (cīvīs) urbem urbēs (urbīs)
Abl. cīve cīvibus urbe urbibus
Voc. cīvis cīvēs urbs urbēs

Neuter i-stem: mare, maris n. sea.

Case Singular Plural
Nominative mare maria
Genitive maris marium
Dative marī maribus
Accusative mare maria
Ablative marī maribus
Vocative mare maria

Exceptions and special forms

  • Masculine and feminine i-stems with ablative in -ī: some nouns in -is may take -ī as well as -e: ignis (ignī, igne), nāvis (nāvī, nāve), cīvis (cīvī, cīve).
  • Accusative singular in -im: a few nouns, such as turris (turrim), sitis, vīs (vim) and the river Tiberis (Tiberim).
  • Accusative plural in -īs is found in older texts and in poetry for i-stems: omnīs, cīvīs.
  • Greek nouns keep Greek endings in part: poēma, poēmatis n., dogma, schēma; the accusative singular in -a (aethera) and plural in -as appear in poetry.
  • Locative: Carthāgō, Carthāginis has the locative Carthāginī (at Carthage); rūs, rūris has rūrī.
  • Irregular and defective nouns such as vīs, bōs, iter, senex and Iuppiter are treated on the next page.

Examples

Homō sum: hūmānī nihil ā mē aliēnum putō.

I am a man: I think nothing human foreign to me. (Terence, Heauton Timorumenos 77; homō, nominative singular)

Ō tempora, ō mōrēs!

Oh, the times! Oh, the customs! (Cicero, In Catilinam 1.2; tempus, temporis n. and mōs, mōris m.)

Gallia est omnis dīvīsa in partēs trēs.

All Gaul is divided into three parts. (Caesar, De Bello Gallico 1.1; pars, partis f., an i-stem, accusative plural)

... genus unde Latīnum, Albānīque patrēs, atque altae moenia Rōmae.

... whence came the Latin race, the Alban fathers, and the walls of lofty Rome. (Vergil, Aeneid 1.6–7; genus n. nominative, patrēs nominative plural, moenia the neuter i-stem plural)

Nōbīs cum semel occidit brevis lūx, nox est perpetua ūna dormienda.

When once our brief light has set, there is one perpetual night to be slept. (Catullus 5.5–6; lūx, lūcis and nox, noctis, feminine nominatives)

Ūnus erat tōtō nātūrae vultus in orbe.

There was one face of nature in the whole world. (Ovid, Metamorphoses 1.6; orbis, orbis m., an i-stem, ablative singular in -e)

Core vocabulary

Masculine

Entry Meaning
rēx, rēgis king
dux, ducis leader
mīles, mīlitis soldier
homō, hominis man, human being
leō, leōnis lion
pater, patris father
frāter, frātris brother
cōnsul, cōnsulis consul
ōrātor, ōrātōris speaker
honor, honōris honour
mōns, montis mountain
mōs, mōris custom
flōs, flōris flower
pēs, pedis foot
hostis, hostis enemy

Feminine

Entry Meaning
māter, mātris mother
lēx, lēgis law
vōx, vōcis voice
pāx, pācis peace
nox, noctis night
lūx, lūcis light
virtūs, virtūtis courage, virtue
aetās, aetātis age
cīvitās, cīvitātis state
nātiō, nātiōnis nation
virgō, virginis maiden
urbs, urbis city
pars, partis part
mors, mortis death
gēns, gentis people, clan
ars, artis art, skill
nāvis, nāvis ship
avis, avis bird

Neuter

Entry Meaning
nōmen, nōminis name
flūmen, flūminis river
carmen, carminis song, poem
corpus, corporis body
tempus, temporis time
opus, operis work
genus, generis kind, race
caput, capitis head
cor, cordis heart
mare, maris sea
animal, animālis animal

Masculine or feminine

Entry Meaning
cīvis, cīvis citizen
canis, canis dog
comes, comitis companion

Parsing practice

Give the case, number and gender (where determined) and the dictionary entry.

  1. rēgī
  2. rēgum
  3. nōmina
  4. cīvium
  5. urbe
  6. maribus
  7. hominēs
  8. corporis
  9. noctis
  10. patrem
  11. flūminī

Answers

  1. Dative singular of rēx, rēgis.
  2. Genitive plural of rēx.
  3. Nominative, accusative or vocative plural of nōmen, nōminis.
  4. Genitive plural of cīvis, cīvis.
  5. Ablative singular of urbs, urbis.
  6. Dative or ablative plural of mare, maris.
  7. Nominative, accusative or vocative plural of homō, hominis.
  8. Genitive singular of corpus, corporis.
  9. Genitive singular of nox, noctis.
  10. Accusative singular of pater, patris.
  11. Dative singular of flūmen, flūminis.

Common pitfalls

  • Guessing the declension from the nominative. The genitive is the signpost; learn it with every noun.
  • Forgetting the stem change. rēx has the stem rēg-, homō the stem homin-, nox the stem noct-.
  • Mixing -um and -ium. The genitive plural of cīvis is cīvium and that of rēx is rēgum.
  • Taking the neuter plural in -a for a first declension singular. nōmina and corpora are neuter plurals.
  • Using -e for the ablative of every neuter i-stem. It is marī, not mare.
  • Guessing the gender from the ending without checking. nōmen is neuter, rēx masculine and lēx feminine.
  • Forgetting that the vocative equals the nominative.
  • Dropping the macron of the plural -ēs. It is long: rēgēs.

Self-test

  1. How do you find the stem of a third declension noun?
  2. Which of these are i-stems, and how can you tell: cīvis, rēx, urbs, mare, corpus?
  3. Give the genitive plural of cīvis, rēx, urbs and mare.
  4. Give the nominative plural of nōmen, mare, animal and corpus.
  5. Give the genitive singular and plural of tempus and genus.
  6. Why does corpus have the stem corpor-?
  7. What is the gender of lēx, rēx, nōmen, pater and mater?
  8. Translate: Rēx cīvēs laudat. Mīlitēs urbem vident. Pater fīlium amat. Nautae mare vident. Homō nōmen scrībit.
  9. What are the two possible ablative singulars of cīvis?
  10. Why is moenia followed by moenium in the genitive?

Answers

  1. Remove -is from the genitive singular.
  2. cīvis (parisyllabic in -is), urbs (monosyllable with two consonants), mare (neuter in -e). rēx and corpus are consonant stems.
  3. cīvium, rēgum, urbium, marium.
  4. nōmina, maria, animālia, corpora.
  5. temporis, temporum; generis, generum.
  6. The original s of the stem (corpos-) became r between vowels.
  7. Feminine, masculine, neuter, masculine, feminine.
  8. The king praises the citizens. The soldiers see the city. The father loves the son. The sailors see the sea. The man writes the name.
  9. cīve and cīvī.
  10. moenia is a neuter i-stem (plural only), so the genitive plural is -ium.

Next: Fourth and Fifth Declensions, Irregular and Defective Nouns

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