It may seem obvious, but "pop" (or, popular) culture requires only one thing: popularity.

That's not to say that something has to be universally popular or even culturally popular. It simply has to be something with considerable appeal within a particular demographic. There is popular science fiction, popular jazz, etc., none of which are necessarily broadly popular among the majority of a given culture.

Beyond popularity, however, you cannot define pop culture.fun, partying dancing n drinkingAnything that is marketed to us, sold to us,consumed by us, disposed of by us , repackaged once more to be sold to us again under the marketed term of being the "new standard of......". Disposable standards.
Ex. ...That Debbie Gibson , Tiffani,Madonna, Brandi,Jessica Simpson, Brittany...ect....ect....there will always be a replacement..Disrepect for QUALITY and FACISM about good things with a negative judgement toward the traditional! In radio the mediocre rules over the sublime!