deklinaatio

Deklinaatio, or declension in English, is the systematic inflection of nouns, pronouns, and adjectives to mark grammatical categories such as case and number, and, in some languages, gender. Through endings or internal changes, a word takes different forms depending on its function in a sentence. Deklination is a morphological system distinct from verb conjugation, which inflects verbs for tense, mood and person.

Most languages with declension organize nouns into paradigm classes or declensions, which govern the set of endings used for each case and number. Adjectives and pronouns typically decline to agree with the noun they modify or refer to.

A familiar example is German. The noun der Hund declines by case: Nominative singular der Hund, Genitive des Hundes, Dative dem Hund, Accusative den Hund. Plural: Nominative die Hunde, Genitive der Hunde, Dative den Hunden, Accusative die Hunde. These endings also affect accompanying articles and adjectives.

Different languages show different extents of declension. English relies largely on word order and prepositions, with only a few remaining case forms in pronouns (he/him, she/her). Other languages use extensive systems: Latin and Russian have multiple cases; German uses four; Finnish and Estonian feature many cases and broad noun inflection.

In a broader sense, declension provides grammatical information such as role in the sentence, possession, or relationship to other words. It supports agreement within noun phrases and can influence syntax and meaning when combined with determiner or adjective forms.