Q. In a Q&A some time ago, you said, “In other words, use the unless the abbreviation is used as an adjective or unless the abbreviation spelled out wouldn’t take a definite article.” My question is: since there is only one definite article in English (the), is a in the expression “a definite article” correct?
A. It’s conventional to refer to “the definite article,” but that doesn’t mean that “a definite article” is nonsense. If there were only one definite article in the whole world available for use, after which no one could use another one, then maybe you would have a point. But we can use the as many times in a sentence as we like—there is an unlimited supply. “The cat climbed the tree in the forest” has three. We can put a [sic] definite article in front of all kinds of words: nouns, adjectives, adverbs, and so on.