Latin declension

Latin noun declension features seven cases:

• nominative (subject)
• genitive (possessive - of which)
• dative (indirect object - to or for which)
• accusative (object)
• ablative (expresses the means or tools by which one accomplishes something)
• vocative (used for addressing another person in direct speech, usually identical to nominative)
• locative (archaic; used to show location in cities, towns, and small islands)

Note: Neuter nouns of all declension classes share two properties:

• The forms for nominative and accusative singular are identical.
• The forms for nominative and accusative plural are identical, and they always end in -a.

As in English, there are two numeri (singular and plural). There are five declension classes:

1. a declension

Nouns of this class usually end in -a and are usually of feminine grammatical gender. Example (paradigma is terra - land, earth):

The a declension has no special forms for the vocative; nominative is used instead. The genitive singular originally had the ending -as (preserved in the expression pater familias) and the dative and ablative plural had -abus (preserved in cum dis et deabus).

Greek words ending in -es or -as (like the name Aeneas) are also declined according to this scheme. They, however, do have a vocative form (stem + -a, e.g. Aenea).

2. o declension

Nouns of this class end in -us, -r or -um. Nouns ending in -us and -r are of masculine gender, those ending in -um of neuter gender.

Example I, words ending in -us (paradigma hortus - garden)

Example II, words ending in -um (paradigma verbum - word)

Example III, words ending in -r (paradigma ager - field)

Note that the e in the nominative singular form is just an insertion to ease pronunciation and is omitted in all other forms. There are however some words, where the e belongs to the stem proper and can't be omitted. These are: gener (son-in-law), socer (father-in-law), puer (boy), vesper (evening) and liberi (children - only occurs in plural forms).

Greek words ending in -eus are declined like regular nouns ending in -us, with the single exception that the vocative singular is formed by appending -u to the "stem" (as in Orpheus - Orpheu)

3. mixed declension

Nouns of this class are divided into two subcategories according to the ending of their stems.

3.1 consonantal stems

This class comprises nouns whose stem ends in a consonant. Some nouns of this class don't have a particular ending for nominative singular. Of these, some use the raw stem instead (as with sol - sun), and some have a special contracted form (like natio - people, tribe). Finally, some consonantal nouns have the nominative singular ending "-s" (like rex - king, which originally was regs). Examples:

3.2: short -i stems

This class consists of nouns whose stem ends in a short -i. According to their nominative form, one can subdivide them into three groups: Some nouns (like nubes - cloud) have nominative forms consisting of the same number of syllables as the other forms, some have shortened nominative forms (like ars - art) and some have non-standard nominative forms ending in -e, -al or -ar (like animal - animal). Examples:

A small group of nouns has a declension scheme especially rich in "i"s. They are: febris - fever, puppis - quarterdeck, securis - axe, sitis - thirst, turris - tower, tussis - cough and vis - power. Example:

4. u declension

Nouns of this class end in -us or -u. The former ones usually are of masculine gender, the latter ones are always neuter.

Example I, nouns ending in -us (paradigma lacus - lake)

Originally, dative and ablative plural ended in -ubus.

Example II, nouns ending in -u (paradigma cornu - horn)

5. e declension

Nouns of this class end in -es. Nearly all of them are of feminine grammatical gender. Example (paradigma dies - day):