it means that person is really drunk (in colloquial german at least)

stubborn, in my onion

Drat, i could had alot of fun with that one;) Well, from my hood, check it, it mean u stiff, yo hard, tough ain't no one gonna steal your bread u feel me? lol i caught Next Friday on cable yesterday :) https://images.app.goo.gl/B7ohDgbfx2d741av9

It means they have a teardrop tattoo on their face

I've never really heard or used it in that sense - unless you mean 'difficult' , as in hard to get along with, disagreeable, etc.

Emotionally cold.

A lump of rock or can be heartless

Hard as in tough? Or hard as in stubborn? Or hard as in zealot?Or hard as in clueless?Or all this together?

i've only heard it once or twice but i got the impression it means they're tough, like they'll fight you and they'll win