Adjective

1. Having an extreme dedication to a certain activity; diehard.

   He's a hardcore gamer.

2. Particularly intense; thrillingly dangerous or erratic; desirably violent in appearance; pleasing or "cool" due to intensity or danger.

   That show was fuckin hardcore, dude.

3. Resistant to change.
4. Obscene or explicit.
5. Of or pertaining to pornography that depicts penetration.
6. Faster or more intense than the regular style.

Noun

1. broken bricks, stone and/or other aggregate used as foundations especially in road and path laying.
2. Hardcore punk or techno music.

   Let's listen to some hardcore.