17.117 Basic Third Declension Endings

When you learn nouns, you should learn both the nominative form and the genitive. This will help you to remember which declension the noun belongs to.

In the first declension, the nominative ending is α or η and the genitive ending is ας or ης (masculine nouns of the first declension have ης in the nominative, with a genitive in ου). In the second declension, the nominative ending is ος (for masculine and feminine nouns) or ον (for neuter nouns), and the genitive ending is ου. It is very easy to recognize the stem of these first and second declension nouns in both the nominative form and in the genitive. The stem does not change.

With third declension nouns, the situation is more complex. It is often difficult to see the stem of the word in the nominative form, so you should look to the genitive form of the noun to identify the stem of a third declension noun. Remove the ending ος from the genitive form, and you will see the stem. This is the stem that you will need in order to generate the other forms of the noun.

Once you have the stem, it is relatively easy to generate the forms. There are often irregularities in the position of the accent, but you will learn the stress patterns for the most commonly found nouns by reading out loud and repeating the words. Note that the genitive plural ending is a long syllable, which often affects the stress of the noun.

As you would expect, most third declension nouns do not have a distinctive vocative form, although there are a few third declension nouns with distinctive vocative forms in the singular.

For the dative plural ending, however, things can get complicated, because the dative plural ending, σι , starts with a consonant, which sometimes mutates when it comes into contact with a consonant-final stem.

Also, a vital point to keep in mind is that neuter nouns are identical in the nominative and the accusative, for both singular and plural. This is true for all neuter nouns - both second declension and third declension (there are no first declension neuter nouns). Also, neuter nouns have alpha as the plural ending in the third declension, just as they do in the second declension.