I have noticed that when occasional is used before a noun then the is used. For example:
The occasional car went by but no taxis.
The watch was designed so as to withstand the occasional knock.
He drank the occasional coffee during the break.
Tell me please if this is the case. And if it is then why is the used not a?
I had no opinion on whether or not "an occasional car" sounded better than "the occasional car," so I decided to experiment with a phrase that sounded more common to my ear — an/the occasional mistake — and run it through Google's Ngram. Then I got curious about what the Ngram would return using "car" instead. This is what was returned:
What this indicates is that either the indefinite article (a/an) or the definite (the) can be paired with the word "occasional" + noun. I don't know if any such pairings would ever be categorized as a colocation, but certainly some pairings will be more common than others and those that are will usually sound more natural even if less common pairings are still technically (i.e., grammatically) correct.
I think "an occasional car" sounds equally good to my ear.
The structure is rather odd, since it is not describing the car, but it means "Cars went by occasionally". It looks like an adjective (syntactically), but works like an adverb (semantically). Its not particularly formal.
But odd or not, either "the" or "an" would work here.
