Latin noun declensions

In Latin, nouns are declined according to how they are used in a sentence. That is, by their case. There are five major cases in Latin, each corresponding to one of the major uses of nouns.

The cases, and an explaination of their function are as follows:

1. Nominative - The nominative case is used for the subject of a sentence, as well as for preidcate nominatives.
2. Genitive - The genitive case is used to express posession, as well as use in the partitive.
3. Dative - The dative case is used for indirect objects, certain special adjectives, as well as a special use called the dative of reference.
4. Accusative - The accusative case is used with the direct object, certain prepositions and for the expression of certain time-space relationships.
5. Ablative - The ablative case is used with the remainder of prepositions, the ablative of means and the ablative of time.

In addition to these five, there is the vocative case, which is used for commands.

In order to express case, nouns in Latin change their endings to express the change. There are five different declensions, or groups by which these changes occur. Those endings are as follows:

Case, I, II, III, IV, V
Singular
Nominative, a, us/er/um, *, us/û, ês
Genitive, ae, î, is, ûs, ei
Dative, ae, ô, î, uî/û, eî
Accusative, am, um/us, em/*, um/û, em
Ablative, â, ô, e/î, û, ê
Plural
Nominative, ae, î/a, ês/a/îa, ûs/ua, ês
Genitive, ârum, ôrum, um/ium, uum, êrum
Dative, îs/âbus, îs, ibus, ibus, êbus
Accusative, âs, ôs/a, ês/a/ia, ûs/ua, ês
Ablative, îs/âbus, îs, ibus, ibus, êbus

Let's start with the 1st Declension. This one isn't too bad to work with. It's done with a song, specifically the ABCs. Sing along like this:

Ay, Ay-Ee, Ay-Ee, Ay-Ehm, long-Ay, Ay-Ee, Ay-Arr-Yuu-Ehm. I-Ess, Ay-Ess, I-Ess too. Now the first declension's through. Isn't Latin so easy? Let's move on to two and three.

Does this little ditty have anything to do with the first declension? Sure it does! Here, take a look...

    Sing.  Pl.
   --------------
Nom -a   | -ae
Gen -ae  | -arum
Dat -ae  | -is
Acc -am  | -as
Abl -á   | -is

Next we'll hit the 2nd declension. This poses slightly more difficulty since it contains both masculine and neuter endings, unlike the almost purely feminine 1st declension. No fear though. This time we'll go with Jingle Bells for our backing tune...

Uhss-ee-oh, um-oh-ee, ohruhm-eess-ohss-eess
Um-ee-oh, um-oh-ah, ohruhm-eess-ah-eess

You'll notice that this time we do not say the letters, instead prounouncing the ending as it would be in Latin. Because the second verse is so close to the first, as neuter endings are so close to masculine endings, it may be difficult to recall which is which. Something that might help would be to note that neuter nouns always, without exception, have the same ending in Nominative and Accusative. Since in masculine the endings are different (us vs. um), you can remember that the ending must be 'a' instead.

    Sing.  Pl.
   --------------
Nom -us   | -i
Gen -i  | -orum
Dat -o  | -is
Acc -um  | -os
Abl -o   | -is

Here's the final one for which I know a memory technique; the 3rd declension. I have to give the credit to a classmate of mine, who came up with an ingenious way of representing the 'various' Nominative endings the third declension can take while still noting all the other ones. Sing this along to If you're happy and you know it clap your hands...

If you're happy and you know it, clap your hands. *clap clap clap*
iss-ee ehm-ay ayss-um ihbus ays-ihbus! *clap clap clap*

The clapping at the very beginning of the second verse represents the different endings the Nominative might take. You have to take some liberty with stressing on the Genitive plural, no real way to keep that from getting separated.

    Sing.  Pl.
   --------------
Nom --   | -es
Gen -is  | -um
Dat -i  | -ibus
Acc -em  | -es
Abl -i   | -ibus

So there you have it, the first three declensions! Knowing them off the top of your head should make Latin translation a great deal easier. Just try not to sing aloud during a test or anything.