Latin students meet nominative and accusative early. Case is a grammatical category that marks the syntactic or semantic role of a noun phrase—subject, object, possessor, and others—through endings or adpositions.

Languages differ in the number of cases they distinguish and in whether case appears on nouns, pronouns, or both. English keeps only faint traces in pronouns. Ergative-absolutive systems group arguments differently from nominative-accusative ones.

Case allows freer word order because role information is marked locally. Historical erosion of case endings often increases reliance on prepositions and fixed order. Grammars catalogue case inventories and the rules that assign them.

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