Just as verbs have conjugations (groups of verbs that share a set of endings), we have declensions of nouns (groups of nouns that share a set of endings). The most common group in Latin is called the 3rd declension. The following nouns that you already know are in the 3rd declension:
canis canis m/f – dog
arbor arboris f – tree
mater matris f – mother
pater patris m – father
frater fratris m – brother
soror sororis f – sister
The first word in the vocabulary listing for nouns is always the nominative singular, and the second is the genitive singular. Then a grammatical gender for the noun is given – either m (masculine), f (feminine), or n (neuter). And some nouns, like canis, are both masculine and feminine.
The thing these nouns have in common is that the second word in the vocabulary listing (the genitive singuar) ends in is. The is ending of the genitive singular is what tells us that the noun belongs to the 3rd declension.
Nouns in the 3rd declension follow this pattern:
|
|
endings |
example |
|
|
Singular |
|
|
Nominative |
-- |
pater father (subject) |
|
Genitive |
is |
patris of a father, father’s |
|
Dative |
ī |
patrī to/for a father |
|
Accusative |
em |
patrem father (direct object) |
|
Ablative |
e |
patre by/with/from a father |
|
Vocative |
same as nominative |
pater O father! |
|
Plural |
|
|
|
Nominative |
ēs |
patrēs fathers (subject) |
|
Genitive |
um |
patrum of the fathers, fathers’ |
|
Dative |
ibus |
patribus to/for the fathers |
|
Accusative |
ēs |
patrēs fathers (direct object) |
|
Ablative |
ibus |
patribus by/with/from the fathers |
|
Vocative |
same as nominative |
patrēs O fathers! |
Note that while the first word in the vocabulary listing gives us the nominative singular, the second one (the genitive singular) is where we get the stem. We find the stem by removing the is from the genitive singular.