A black body absorbs all light/radiation in its reach. According to basic laws of physics, the more energy a body absorbs the more it can emit. Therefore, a black body absorbs all energy directed at it and also emits all energy that's been absorbed.
A black hole is known to absorb all sorts of every (light, radiation..). If it absorbs -all- energy around it, it should in addition emit all energy it has absorbed. But due to its vast gravity noting can "escape", and therefore nothing is actually emitted. Is a black hole still considered a perfect black body?
Disclaimer: I am no physicists, I am a senior year high school student with an interest for physics. I don't know the preferred terminology of things, especially not in English (2nd language), so if anything is unclear I will explain in comments below.