black hole 
noun
1 Astronomy A region of space having a gravitational field so intense that no matter or radiation can escape.This universe is very similar to our own, with thousands of stars and galaxies, black holes, comets and meteors each a part in the never-ending celestial dance....
- An astronomy satellite that studied black holes and distant galaxies was wiped out by the one star that it did not watch.
- Some of the invisible dark matter that is missing from the Universe may be massive dark bodies such as planets, black holes, asteroids or failed stars.
1.1 informal A place where money or lost items apparently disappear without trace.It's like a big black hole, the money disappears....
- The single biggest problem with the privatisation programme is that the proceeds disappear into a black hole called the Consolidated Fund of India.
- Critics predicted that, without radical change to make the service more accountable, the money would disappear into a black hole.
Black holes are probably formed when a massive star exhausts its nuclear fuel and collapses under its own gravity. If the star is massive enough no known force can counteract the increasing gravity, and it will collapse to a point of infinite density. Before this stage is reached, within a certain radius (the event horizon) light itself becomes trapped and the object becomes invisible.