How do noun case endings work in Eastern Armenian?

In Eastern Armenian, noun case endings function through a system of agglutination that resembles the structures found in Turkish or Georgian. Unlike Old Armenian, which utilized different endings for singular and plural forms, Eastern Armenian typically applies the same endings to both.1

To form the plural, an infix—most commonly -ner-—is inserted between the noun stem and the case ending. For example, the word ašakert (pupil) becomes ašakert-i (of/to pupil) in the singular and ašakert-ner-i (of/to pupils) in the plural.1

Key features of the Eastern Armenian case system include:
* Locative: The language features a specific locative ending, -um.1
* Ablative: Eastern Armenian uses the ending -ic‘ to denote the ablative case (e.g., Hayastan-ic‘, meaning "from Armenia"), distinguishing it from Western Armenian, which retains the older -ē ending.1
* Definite Article: The definite article (-ə after consonants, -n after vowels) interacts with case endings; notably, in Eastern Armenian, the definite article is generally not used following the genitive case.1

Modern Eastern Armenian declension has evolved significantly from its Indo-European roots, prioritizing these consistent, agglutinative patterns.1