Nouns

What is a Case?

A case, in Latin, is a grammatical term to indicate a change that occurs usually in the ending or terminus of a nounor adjective (puella, puellae, puellam). Sometimes the whole word changes. (is, eius, eam).
The reason for cases in Latin is to indicate how a word functions within a sentence. There are cases in English that are obvious in pronouns. He is a nominative case and him is an accusative case.
Since word order is not mandated in Latin, it is the case ending that indicates whether a noun is the subject, direct object or object of a preposition. The case of an adjective must be the same as the noun it modifies. Therefore, even if a noun and adjective are not placed next to one another, the reader knows that they belong together.
In English we use we as the subject of a sentence. One never says "He saw we in a store" or "My friend went with we to the market." In place of the nominative we, one needs to use the accusative form US as either the direct object of a verb (He saw US or I went to the store with US)

Latin has five cases, six when one counts the vocative which usually is the same as the nominative form and thus sometimes not listed as a separate case.

Nominative - subject of a sentence or predicate noun
We saw the game...subject is We; They were friends. Friends = they so both are nominative.
Compound subjects - My friend and I went to the game...both friend and I are nominative.

Genitive - possession (of ..., ______'s, _____s' and root of the word
I am the daughter OF a wonderful woman...both wonderful and woman are genitive singular

Dative - indirect object with verbs of giving, telling, saying
I gave something to someone...the 'to someone' is dative and one does not write 'to' in Latin; the dative case indicates the 'to'. One uses 'to' only with direction.

Accusative - direct object of a verb; object of many Latin Prepositions
When one has a transitive verb, a verb that can have a direct object such as 'see', it is usually followed by a direct object. The dog sees the cat. Dog is the subject, nominative sg. and cat is the direct object, accusative sing. In English we know the dog is doing the action and the cat receiving it because of the word placement. In Latin I can write 'felem canis videt' or 'canis felem videt' and because of the noun endings, I know that the dog is seeing the cat and not the reverse.
There will never be a direct object with an intransitive verb. Intransitive verbs are forms of 'to be' and many action verbs such as 'run' or 'walk'. One can recognize these verbs in a dictionary when the fourth principal part ends in 'urus' rather than 'us'. More VERB information can be found on the verb section of the grammar pages.
The accusative case usually follows most prepositions as well as in 'canis prope villam ambulat' which says 'The dog is walking near the farmhouse'.

Ablative - prepositional phrases with or without Latin prepositions as well as many other uses which you will learn as the year progresses. You can also find out more about the ablative uses in Grammatica under Latin II. When you see an ablative form and there is no Latin preposition, translate as 'by means of' or merely 'by' or 'with'.
e.g. He was hit with a stick...by means of a stick.
When the name of a town, city, or small island is in the Ablative case, use 'from'. e.g. Venit Româ- He comes from Rome.
The ablative can also show MANNER. e.g. magnâ voce - with a loud voice
The ablative can indicate the TIME WHEN something occurred. e.g. primâ luce - at dawn
The ablative is also used with a select group of prepositions that fit the acronym SID SPACE. Thanks to Sally Davis for this acronym! Sub In De Sine Pro A(b) Cum E(x) are the prepositions which are followed by ablative nouns. Note that In means In or On when the ablative is used whereas it means INTO when followed by the accusative case.

Vocative - direct address
The vocative form is the same as the nominative except for masculine singular nouns ending in 'us' or 'ius' such as Marcus and Lucius. e.g. Marce, get up!, Luci, wash the dishes! All plural forms are the same as the nominative.

^ Grammatica