Noun

1. 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 determiners include articles (a, the), demonstratives (this, those), cardinal numbers (three, fifty), and indefinite numerals (most, any, each).
2. A dependent function in a noun phrase marking the NP as definite or indefinite. This function is usually filled by words in the determinative class but may be filled by other elements such as a genitive pronoun.
3. Something that determines, or helps someone to determine, something else.
   • 1901: Azel Ames, The Mayflower and Her Log

     The "steel-yards" and "measures" were the only determiners of weight and quantity — as the hour-glass and sun dial were of time — possessed at first (so far as appears) by the passengers of the Pilgrim ship,

See also

• article
• demonstrative