Definitions
1.nounA place of punitive confinement; a lockup or cell; a military guardroom.
2.nounA gravitationally domineering celestial body with an event horizon from which even light cannot escape; the most dense material in the universe, condensed into a singularity, usually formed by a collapsing massive star.
3.nounA void into which things disappear, or from which nothing emerges; an impenetrable area or subject; an area impervious to communication.
4.nounA place where incoming traffic is silently discarded."One way of fighting spam is to use a blackhole list maintained on a blackhole server."
5.nounA bit bucket; a place of permanent oblivion for data.
6.verbTo redirect (network traffic, etc.) nowhere; to discard (incoming traffic).