noundeclension

Noun declension is the set of inflectional patterns that nouns in a language undergo to express grammatical categories such as case, number, and sometimes gender. In languages with noun declension, nouns take different forms depending on their syntactic role (for example, subject or object) and their quantity. The changes are typically realized through endings, though some languages use internal vowel changes or stem modifications as well.

Across languages, the specifics of noun declension vary widely. Many Indo-European languages—Latin, Greek, German, Russian, and others—feature robust noun declensions with multiple case distinctions. English, by contrast, has largely reduced noun inflection, retaining mainly a plural suffix and possessive marking in modern usage. In languages with gender systems, noun gender often interacts with determiner and adjective agreement, adding another dimension to declension patterns. Nouns are usually organized into declension classes or paradigms, each with characteristic endings or stem-altering rules.

Common cases express roles such as nominative (subject), accusative (direct object), genitive (possession), and dative (indirect object), among others. Some languages include more cases (for example, Russian with six) and several numbers (singular and plural). Declension is closely connected to other parts of grammar; adjectives and articles frequently agree with the noun in case, number, and gender.

Declension systems are studied in morphology and historical linguistics to understand how noun forms emerge, shift, and influence sentence structure over time. Variations in declension reflect fundamental differences in how languages encode grammatical relations and organize noun-related meaning.