| Acronym | Definition |
|---|
| HALO | High Altitude Low Opening (parachuting) |
| HALO | Helping and Leading Others (est. 2009) |
| HALO | Halation (cinematography) |
| HALO | High Altitude Observatory |
| HALO | Hispanic American Leadership Organization (student organization) |
| HALO | Hostile Artillery Locator (BAE Systems) |
| HALO | Highly Advanced Loader Operations (paintball) |
| HALO | Hazardous Area Life-Support Organization (Humanitarian aid organization and trust fund) |
| HALO | High Altitude Large Optics |
| HALO | High Amount Lock Out (stocks) |
| HALO | High Articulation Laser Optics (Reston, VA) |
| HALO | High Altitude Low Orbit (game) |
| HALO | High Altitude Low Observable |
| HALO | High Altitude Long Operating (Angel Technologies) |
| HALO | Hypersonic Aircraft Launch Option |
| HALO | Hematopoietic/Hemotoxicity Assays Via Luminescence Output (HemoGenix) |
| HALO | High Availability Load Optimizing (web hosting) |
| HALO | Help a Loser Out |