In grammatical theory, definiteness's a feature of noun phrases, distinguishing between entities which are specific and identifiable in a given context (definite noun phrases) and entities which aren't (indefinite noun phrases). There's considerable variation in the expression of definiteness across languages: some languages use a definite article (which can be a free form, a phrasal clitic, or an affix on the noun) to mark a definite noun phrase. Examples are: Phrasal clitic: as in Basque: Cf.… (More on Definiteness)