Definitionen
1.NounA place of punitive confinement; a lockup or cell; a military guardroom. .mw-parser-output .defdate{font-size:smaller}
2.NounA region of spacetime that exerts a gravitational pull strong enough that no matter or energy, not even light, can escape it.
3.NounA void into which things disappear for good; an inscrutable area or subject.
4.NounA dangerous optical illusion that can occur on a nighttime approach with dark, featureless terrain between the aircraft and a brightly-lit runway, where the aircraft appears to the pilots to be higher up than it actually is, potentially triggering a premature or overly-steep descent and a crash short of the runway.
5.NounA place where incoming traffic is silently discarded."One way of fighting spam is to use a blackhole list maintained on a blackhole server."
6.NounA bit bucket; a place of permanent oblivion for data.
7.VerbTo redirect (network traffic, etc.) nowhere; to discard (incoming traffic).