(adj) used to describe anything really far out and amazing, not necessarily lovely; an extraordinary stunt, or event.  A word that is overused by the cast of Laguna Beach. It means crazy, rad, totally awesome. A slang term for something extreme. Used in bad and good cases. Originated from the word gnarled - grotesque, yet awesome.
Original from 70's surfspeak - to describe waves that are violently breaking without the form that would render them more rideable. Can also describe less than ideal females.
- These kooks have no idea what GNARLY is. Gnarly is when you've gone beyond radical, beyond extreme, it's balls out danger, or perfection, or skill or all of that combined.
-  That scar's fucking gnarly
- Gnarly, Dude: Google Solves Rubik’s Cube In 20 Moves
- Try riding this, dude: The world's largest skateboard that is bigger than a bus!
- That was gnarly, dude!!!
- Nobody can shred like that guy, he's fuckin gnarly.
- Pipeline in the winter is fucking GNARLY!
- That was a fucking gnarly wreck man, that dudes head flew off.
- Did you see that new Local Motion board? It is gnarly.
- That was/is SO gnarly!
- That was a gnarly wipe out !!! (off the hook , totally extreme)