Definition from Wiktionary, the free dictionary
- (aviation, parachuting) High Altitude, Low Opening. — a type of skydiving, where you leave the launch platform from a high altitude, and open the parachute at a very low altitude.
- When you have enough experience, you can do a HALO jump.
- Hazardous Area Life-Support Organisation
HALO also means High Altitude, Low Orbiting. As used in reference to certain aviation crafts. For example, weather balloons, when at maximum altitude are considered HALO's.