Sijamuodon

Sijamuoto, or case form, is a central grammatical category in Finnish that marks the noun’s or pronoun’s function within a sentence. Through suffixal inflection, words change their shape to indicate roles such as subject, direct or indirect object, possession, location, or movement. Finnish nouns usually inflect for case, and adjectives and numerals agree with the noun in sijamuoto as well.

Finnish has a rich system of cases, commonly described as a set of around 15 forms in traditional grammars. These include the nominative, genitive, partitive, and several locative or modal cases such as inessive, elative, illative, adessive, ablative, allative, essive, translative, and abessive. Some grammars also mention historical or less productive forms such as comitative or instructive. In everyday language, speakers typically use a core subset of these cases, while the full system provides a wide range of expressiveness for spatial, aspectual, and temporal relations.

Illustrating with the noun talo (house) in singular forms: nominative talo; genitive talon; partitive taloa; inessive talossa; elative talosta; illative taloon; adessive talolla; ablative talolta; allative talolle; essive talona; translative taloksi; abessive talotta. Form changes depend on phonology and vowel harmony, and some nouns may undergo consonant gradation or other stem alterations. Plural forms follow their own patterns but generally keep the same case endings.

Sijamuoto plays a decisive role in Finnish syntax and meaning, enabling flexible word order while conveying precise grammatical relations. Mastery of the case system is essential for correct noun modification, agreement, and comprehension in Finnish.