Plain English Meaning
When the air pressure around you drops too fast, gas that was dissolved in your blood and tissues turns into bubbles, like opening a fizzy drink. Those bubbles can cause pain, dizziness, breathing trouble, or worse.
Full Definition
A medical condition caused by nitrogen dissolved in the body's tissues and blood coming out of solution and forming bubbles when surrounding pressure drops too quickly. In aviation it occurs when a pilot ascends to high altitude (typically above 18,000 feet, but possible lower) or flies soon after scuba diving. Symptoms range from joint pain and skin itching to neurological problems, breathing difficulty, and collapse.
Context Anchor
Seen in high-altitude physiology discussions, especially when about use, , rapid , and flying after scuba diving.