But I’m wondering: Here in the good ol’ U.S. of A., did the term perhaps originate from the construction of baseballs?
Little kids learning the basics of baseball will often use a ball that’s the same size as a real baseball, but made out of foam rubber (a “soft core”, as it were). Real baseballs, on the other hand, will be made of a layer of bleached leather covering yarn that’s been tightly wound around a cork core, so as to be rather hard.
So, does the American usage of “hardcore” to mean someone or something that’s “serious” or “earnest” come from baseballs?
It also appears, according to that site, that “hard-core” as slang for “tough” in general comes from 1951.
While this is certainly well after baseball became the National Pastime, it might not be that long after the introduction of soft-core “practice” baseballs for youngsters learning the basics of the sport.
I doubt it. Kids called them hardballs (and that term comes from baseball), softballs, spaldeen (rubber balls used for stickball) and whiffle balls (for the company that made the hollow plastic baseballs). I never heard of a hardball being called “hardcore” in a baseball context.
I suspect that “hardcore” evolved from “hard-hearted”. “Heart” is/was frequently used to refer to the center of some things: heartwood is the wood at the center, or core, of a tree, for example. Figuratively speaking, a person’s heart is their center, or core, and “hardened” criminals are often hard-hearted. This could have been conflated with the phrase “rotten to the core”, and you end up with “hardcore”.