Latin students learn nominative, accusative, and genitive early. Case is a grammatical category that marks the syntactic or semantic role of a noun phrase—such as subject, object, or possessor—often through inflectional endings or adpositions.

Languages differ in how many cases they distinguish and whether case appears on nouns, pronouns, or both. English retains only faint traces in pronouns (I/me, she/her). Ergative-absolutive systems organize case differently from nominative-accusative systems, grouping the subject of an intransitive verb with the object of a transitive one.

Case helps listeners assign roles even when word order varies. Historical change can erode case endings and increase reliance on prepositions and fixed order. Descriptive grammars catalogue case inventories and the rules that assign them.

• Marking of a noun phrase’s grammatical role
• Often expressed by inflection or adpositions
• Inventories and alignments differ across languages
• Supports flexible word order when robust