One of a limited class of noun modifiers that determine the referents of noun phrases WordNet 3.0 & Open English WordNet

A determiner, also called determinative, is a word, phrase, or affix that occurs together with a noun or noun phrase and generally serves to express the reference of that noun or noun phrase in the context. Wikipedia

Part of speech reflecting the reference of a noun Wikidata

A noun modifier that expresses the reference of a noun or noun phrase in the context, including quantity, rather than attributes expressed by adjectives. OmegaWiki

A member of a class of words functioning in a noun phrase to identify or distinguish a referent without describing or modifying it. Examples of determinatives include articles (a, the), demonstratives (this, those), cardinal numbers (three, fifty), and indefinite numerals (most, any, each). Wiktionary

A member of a class of words functioning in a noun phrase to identify or distinguish a referent without describing or modifying it. Wiktionary

Class of words. Wiktionary (translation)