Costanice retains a system of three cases and two numbers in nouns, although the system is heavily altered by sound change and analogy compared to the original Greek system. There are three genders and three classes of nouns, which are discussed in this article together with the definite article and some etymological information. The noun classes are numbered according to their traditional classification.

First Declension

The first declension in Costanice contains mostly feminine nouns, with a handful of irregular masculine nouns added in. The regular feminine noun sixe "soul" has the following declension:

As you can see, the stem of this word is six-, and the final vowel varies according to case and number. There is quite a bit of homophony between different members of the declension, mostly due to phonological leveling. A masculine noun in this declension would have exactly the same endings. All of the endings in this declension that do not end in /s/ take /n/ as an epenthetic consonant under liason.

ETYMOLOGY: The first declension has suffered the least from analogical leveling. The sound changes leading to the declension above are quite simple: loss of final /-n/, loss of vowel length distinctions, and the leveling of /-ai/ to /-e/. The only other thing that needs to be noted is the loss of a distinct accusative case as the historical nominative fell out of use, and the accusative rose to take its place. Throughout the remaining declensions the exact same loss of the nominative has taken place.

Second Declension

The second declension contains mostly masculine and neuter nouns, with a handful of feminine nouns. A typical masculine noun is cirio, "Lord, sir, mister."

Once again, all of the nouns in this declension add /-n/ to the forms that end in a vowel under liasion. A feminine noun in this declension has the same endings, but uses the feminine article illustrated above.

ETYMOLOGY: The nominative forms are regular developments from the old Greek accusatives in both the article and the noun ending. The genitive plural is likewise regular (though it has become homophonous with the nominative singular), but the ending of the noun in the genitive singular has acquired an /-s/ through analogy with the first and third declensions. The masculine genitive singular article, however, has not been modified by analogy. Thus the genitive singular and nominative plural are indistinguishable by the form of the noun alone, but are distinct when taken together with the article. In the dative, the plural ending /-es/ is a regular development of /-ois/ (by means of /-ys/, then /-is/), but the singular ending has become /-e/ by analogy with the other two declensions. (And because the regular outcome would have been /-o/, which was evidently too much homophony even for the Costanicos.)

A typical neuter noun in this declension is prosuebo, "face, person."

As you can see, this declension is identical in every way to the masculine declension except for the nominative plural, which takes /-a/ in place of /-os/. However, under liason neuter nouns in the nominative do not add /-n/, but rather lose their final vowel.

ETYMOLOGY: In general vowels that are lost under liason represent original short final vowels. Thus it is expected that the final /-a/ of the neuter noun declension would disappear under liason, but unexpected that the neuter noun ending /-o/ would also be lost, since it descends from original /-on/. Here the liason form appears to be based on the article, which was /to/ even in Greek, and thus susceptible to liason. It may also be based on the liason of neuter nouns in the third declension. This noun class has also absorbed original 3rd-declension neuter nouns of the genos type.

Third Declension

The third declension contains masculine, feminine, and neuter nouns, and is the largest declension. A typical third declension noun is nita, "night" (a feminine noun).

As with the other declensions, these forms that end in vowels all add /-n/ under liason. These endings are only for masculine and feminine nouns--neuter nouns use a different system which is described below.

ETYMOLOGY: In Costanice, the third declension has absorbed a great many nouns that did not originally belong to it, such as feminine nouns ending in short /a/ and those nouns that in Koine end in /a/ because the previous letter is /r/, /i/, or /e/. These nouns have in turn exerted analogical influence on the rest of the paradigm. Thus, the nom. sg. ending /-a/ adds /-n/ under liason, rather than disappearing, and the dat. pl. ending is /-es/ rather than some reflex of Koine /-si(n)/. (The original dat. pl. ending was also abandoned because it wrought havoc on the stems of nouns it as attached to.)

The neuter nouns have the same underlying declension, but they add to their stem in all forms of the paradigm except the nom. sg. A typical such noun is xriema, "thing, goods.":

ETYMOLOGY: The etymology of these nouns should be pretty clear. Some neuter nouns that were not originally declined with /-ma(t)/ in Greek were drawn into this class by analogy.

There is a subclass of masculine and feminine nouns in the third declension which has a few peculiarities--namely, stress regularly on the antepenult syllable and a few peculiarities of the endings. For example, pólea, "city".

ETYMOLOGY: This class now contains both original polis-type nouns and basileus-type nouns. The endings of these nouns were similar in any case, and analogy eliminated the differences and fused these two groups.