Latin first declension
Description
Latin words of the first declension have an invariable stem and are generally of feminine gender. The predominant letter in the ending forms of this declension is a. The nominative singular form consists of the stem and the affix -a, and the genitive singular form is the stem plus -ae.
There is a small category of masculine exceptions, which generally refer to occupations. These include 'farmer' (agricola, agricolae masc.), 'sailor' (nauta, nautae masc.), 'charioteer' (aurīga, aurīgae masc.), 'inhabitant' (incola, incolae masc.), 'pirate' (pīrāta, pīrātae masc.), 'writer' (scrība, scrībae masc.), and 'poet' (poēta, poētae masc).
The first declension also holds three types of Greek nouns, derived from Ancient Greek's Alpha Declension. They are declined irregularly in the singular. Occasionally, these Greek nouns may be declined as if they were native Latin nouns, e.g. nominative athlēta may be used instead of the original athlētēs.
The older genitive singular termination is an –ās. This is often used with familia as in pater familiās and māter familiās.
In poetry, the genitive singular –āī occurs. Aquae becomes aquāī.
The genitive plural ending –um replaces –ārum. This is actually a contraction. Puellum.
Because first declension nouns and second declension nouns display an –īs in the dative and ablative plural, words likeequus (horse) and equa (mare) will end up looking alike in these cases. However, if a distinction must be made, equīsfor 'mares' would become equābus in the dative and ablative plural. For this reason, the ending -ābus was regularly used in the dative and ablative plurals of the nouns dea (goddess) and filia (daughter).
Notes:
The plural and dative singular forms equal the forms of pure Latin words.
Examples:
Latin words of the second declension are generally of masculine gender (ending in -us) or neuter gender (ending in -um), and have a genitive in -ī.
Latin words borrowed from Ancient Greek’s second declension are inflected with a varying mixture of Greek and Latin endings.
Notes:
‡¹ In antique Latin, words ending in -ius or -ium take the ending -ī in genitive singular. e.g. in antique times, fīliusbecame fīlī in the genitive singular (later and nowadays fīliī), and negōtium became negōtī (later and nowadays negōtiī).
‡² * Words ending in -ius and -ius becomes ī. E.g. fīlius becomes fīlī in vocative singular.
Examples:
N.B.
The singular vocative of second declension -us nouns is the only place in pure Latin words in which the vocative ever differs from the nominative forms: -e instead of -us. The plural vocative is the same as the nominative. As seen in filius, filiī, the vocative singular changes the -ius into an -ī, instead of changing the -us into an -e.
deus, -ī m has several irregular plural forms.
Greek declension
Examples:
atomus (-os), -ī, f
ampelos, -ī, f
mȳthos, -ī, m
phaenomenon, -ī, n
N.B.
Genitive, dative, ablative, locative and usually also the plural are the same as in Latin words; for -os/-us it is like Latin -us and words with stem in r/er, and for -on/-um it is like Latin -um.
In case of proper nouns and book titles genitive plural -ōn and nominative plural -oe can appear, as in Vergil'sGeorgicon Libri alias Georgica and in Terence' Adelphoe.
Latin nouns of the third declension comprise consonant stems and i-stems (e.g., as the i in the neutral genitive pluralanimalium). They are of all three genders, and have genitives in -is. The forms of the nominative and vocative singular are identical to each other and are often quite different from other cases, in which case both stems are given in citation forms.
Words borrowed from Greek's third declension are inflected with a varying mixture of Greek and Latin case endings.
Consonant stem
Citation form: homō, hominis m
Neuter consonant stem
Citation form: nōmen, nōminis n
I-stem
Citation form: turris, turris f
"Pure" i-stem
Citation form: animal, animālis n
Mixed declension (mixed i-stem)
Citation form: nox, noctis f
Greek declensions
Citation form: āēr, āeris m, sometimes f
Citation form: tigris, tigridis m and f
Similiar to i-stem declension:
Examples:
Several feminine proper nouns from Greek end in -ō, genitive in -ūs, such as: Aëllō, Allēctō (Alēctō), Argō, Brīmō, Callistō,Calypsō, Celaenō, Cētō, Chariclō, Clīō, Clōthō (Clōtō), Dīdō, Drȳmō, Ēchō, Enȳō, Eratō, Erichthō, Hērō (Erō), Īō, Īnō, Lātō,Lētō, Mantō, Melanthō, Pērō, Polyxō, Pȳthō, Sapphō, Theānō, Tȳro, Xanthō.
Notes:
Some of these nouns have regular third declension forms.
While these words usually belong to the third declension, some English-speaking grammarians (incorrectly) put them to the fourth declension.
Latin nouns of the third declension comprise consonant stems and i-stems. The consonant stems include the comparativeform of adjectives. This declension is divided into three subcategories: adjectives of one termination (which includes present participles), adjectives of two terminations (one for m and f, and one for n), and adjectives of three terminations (which are generally -er m, -ris f and -re n).
One-termination consonant stem
Citation form: vetus, -eris
One-termination i-stem
Citation form: atrōx, -ōcis
Two-termination consonant stem (comparatives)
Citation form: melior, -us
Two-termination i-stem
Citation form: tristis, -e
Latin words of the fourth declension are generally masculines or, less commonly, feminines in -us and neuters in -ū. The genitive is in -ūs.
The dative-ablative plural -ibus may less commonly appear as -ubus.
Masculine or feminine -us form