Hard refuse matter, such as fragments of demolished walls, that may be re-used in the foundations of new structures (paraphrasing the _Oxford English dictionary_ http://dictionary.oed.com/cgi/entry/50050166?search_id=y2PI-exIYWn-16920&query_type=word&queryword=hardcore&result_place=1&first=1&sort_type=alpha&hilite=50050166se1&max_to_show=10)

Sexually explicit material that graphically depicts the genitals and sexual acts.

stubbornly resistant to change or improvement; "hard-core addicts"

intensely loyal; "his hard-core supporters"

extremely explicit; "hard-core pornography"

Explicit images or movies of couples or groups of people having sexual contact and penetration of any orifice.

1. Sexual pictures, movies, etc. that show genitals, especially an erect penis, and often include penetration. Opposite of SOFTCORE. 2. Intense or dangerous sexual activity.

depictions of two or more guys having sex.

Genres displaying intense melodramatic loyalty to specific characteristics of a style.