Case role

Case roles, according to the work by Charles Fillmore (1967), are the semantic roles of noun phrases in relation to the syntactic structures that contain these noun phrases. The term case role is most widely used for purely semantic relations, including theta roles and thematic roles, that can be independent of the morpho-syntax. The concept of case roles is related to the larger notion of Case (with a capital letter C) which is defined as a system of marking dependent nouns for the type of semantic or syntactic relationship they bear to their heads. Case traditionally refers to inflectional marking.

The relationships between nouns and their containing structures is one of both syntactic and semantic value. The syntactic positional relationships between forms in sentences varies cross-linguistically and allows grammarians to observe semantic values in these nouns by examining their syntactic values. Using these semantic values gives the base for considering case role in a specific language.

Case theory includes, in addition to its inventory of structural cases, a series of lexical cases that are assigned at deep-structure in conjunction with theta role assignment. In addition to its relation to Case (case based on syntactic structures), these semantic notions of case role are closely related to morphological case as well.