This paper investigates the notion of definiteness from a psycholinguistic perspective and addresses Löbner’s (1987) distinction between semantic and pragmatic definites. To this end inherently definite noun phrases, proper names, and indexicals are investigated as instances of (relatively) rigid designators (i.e. semantic definites) and contrasted with definite noun phrases and third person pronouns that are contingent on context to unambiguously determine their reference (i.e. pragmatic definites). Electrophysiological data provide support for this distinction and further substantiate the claim that proper names differ from definite descriptions. These findings suggest that certain expressions carry a feature of inherent definiteness, which facilitates their discourse integration (i.e. semantic definites), while others rely on the establishment of a relation with prior information, which results in processing cost.