The term 'indefinite article' refers to the two English words 'a' and 'AN'. These words are used before nouns to indicate that the noun is unspecified or unknown. They are also used to refer to something in general, rather than a specific item. For example, 'a dog' could refer to any dog, while 'the dog' would refer to a specific dog. The indefinite article is AN important part of English grammar, and is used to make sentences more precise.