casemarking

Case marking is a grammatical system in which nouns and certain pronouns carry markers—affixes, clitics, or prepositional forms—to indicate their grammatical role in a clause. Common cases include nominative for the subject, accusative for the direct object, genitive for possession, and dative for the indirect object. In many languages, adjectives and determiners agree in case with the nouns they modify, and pronouns retain distinct case forms.

Typologically, case marking is diverse. In nominative-accusative languages, the subject of both transitive and intransitive verbs is treated similarly, while the object is marked differently (examples include Latin and Russian). In ergative-absolutive languages, the subject of an intransitive verb behaves like the object of a transitive verb, while the agent of a transitive verb is marked separately (examples include Basque and Georgian). Some languages exhibit tripartite systems, with three distinct case alignments, though these are relatively rare. Many languages also show differential object marking (DOM), where definite or animate objects receive explicit case marking or clausal markers, while indefinites or inanimates may not.

Markers appear as suffixes or prefixes on nouns, as postpositions, or as clitics attached to the noun phrase; in some languages, case is primarily expressed through prepositions. Pronouns often have the most extensive case inventories, whereas nouns may show limited or no case marking. Case marking interacts with word order: languages with rich case systems can have flexible word orders, while languages with little case marking typically rely on syntax to convey roles.

Across languages, case marking can be lost or reduced over time, or restructured through contact or grammaticalization. It remains a central feature for encoding grammatical relations and argument structure in many language families.