Well, Cloister Black is a type of font that is AWESOME!!! It is not used that often but looks really cool! If you want to see it go to this link http://www.dafont.com/Cloister-Black.Font YOU'LL REALLY LOVE IT!!
I'm not exactly sure, but they usually accept being called black, but if you want to be polite say dark, or nothing about their skin at all. I have tried not to be offensive in these statements.
Perfect black would be the inability for any light at all to reflect off the surface. A black hole is black because light cannot escape the gravitational pull.