caseusage

Caseusage is a term used in linguistics to describe how languages express grammatical relations through case on nouns, pronouns, and related modifiers. It covers the systems by which case is assigned and realized, including morphological case marking (such as suffixes or postpositions) and the use of word order or prepositions to indicate grammatical roles. Case usage marks core relations such as subject, direct object, indirect object, possession, and various oblique roles, and interacts with agreement and syntax.

Linguistic systems vary widely. Nominative–accusative languages typically mark subjects and objects differently, with languages like German showing rich inflection and article agreement. Morphologically rich languages such as Russian use multi-case inventories, while Finnish has a particularly large set of cases and Turkish uses suffixal marking on nouns. Other languages rely more on fixed word order and prepositions rather than heavy inflection.

In typology, ergative–absolutive alignment offers an alternative pattern of case usage, wherein the subject of a transitive verb is treated differently from the subject of an intransitive verb. Some languages exhibit split ergativity, and many show case syncretism or zero-case marking, where no overt case is visible on the noun.

Beyond theoretical study, case usage is important in natural language processing, language education, and lexicography, helping with parsing, machine translation, and semantic-role labeling.