2. A chronic lung disease characterized by the deposit of coal dust, smoke, and carbon in the lungs and by the formation of black nodules on the bronchioles.
2. Statutes passed by pro-slavery, Southern states of the U.S.A. before and after the Civil War, which were meant to limit the civil rights of slaves or freed slaves.
All black codes were eventually repealed.
These black dermatographias appear within minutes, in some cases accompanied by itching.
In normal situations, the swelling of black dermatographias will decrease without treatment within 15–30 minutes; however, in extreme cases, itchy red welts may last anywhere from a few hours to several days.
2. An object whose matter has become so condensed that its gravitational field is striking enough to prevent light escaping from it.
3. In theory, a collapsed object (perhaps a massive star) whose gravitational field is so strong that under most circumstances no light or matter can escape.
The term was invented by the American physicist John Wheeler in 1968 (some sources say 1967). Within a few years, other usages had expanded the phrase for other applications; such as, to describe everything from large budget deficits to gaping legal loopholes.
The "black hole" is also used as a verb. In technological circles, to "black-hole" means to cut off data going to and coming from an address, particularly an address used by a spammer. This usage has been around since about 1997.