Singular
* -s: Nominative (subject) - _fīlius_ (son)
* -is: Genitive (possession) - _fīliī_ (of a son)
* -ī: Dative (indirect object) - _fīliī_ (to/for a son)
* -em: Accusative (direct object) - _fīlium_ (a son)
* -e: Ablative (by/with/from) - _fīlie_ (by/with/from a son)
Plural
* -ēs: Nominative (subject) - _fīliī_ (sons)
* -um: Genitive (possession) - _fīliōrum_ (of sons)
* -ibus: Dative (indirect object) - _fīliibus_ (to/for sons)
* -ēs: Accusative (direct object) - _fīliōs_ (sons)
* -ibus: Ablative (by/with/from) - _fīliibus_ (by/with/from sons)
Important Notes:
* Stem Changes: The ending is added to the stem of the noun. The stem is the base form of the noun without the nominative singular ending. For example, the stem of _fīlius_ is _fīli_.
* Exceptions: There are some nouns that have irregular declensions in the third declension, such as nouns with stems ending in -r, -l, or -n.
* Gender: While the above endings are for masculine nouns, 3rd declension nouns can also be feminine or neuter.
* Context: The specific case ending will depend on the noun's function in the sentence.
Remember, understanding the different declensions and their endings is crucial for interpreting and translating Latin. If you're learning Latin, it's a good idea to practice these endings with different nouns to solidify your understanding.