| Acronym | Definition |
|---|
| HDO | High Definition Optics (various companies) |
| HDO | Health Delivery Organization (various organizations) |
| HDO | High Density Overlay (phenolic resin-impregnated plywood used in concrete forms) |
| HDO | Human Development Organization (Sri Lanka) |
| HDO | Holy Day of Obligation |
| HDO | Hearing Designation Order (FCC proceedings) |
| HDO | Healthcare Discount Organization (Addvantage Care) |
| HDO | Heavy Duty Oil |
| HDO | High Demand Occupation |
| HDO | Humanitarian Demining Operation |
| HDO | Hydrogen Deuterium Oxide |
| HDO | Headache During Orgasm |
| HDO | Homeland Defense Office |
| HDO | Housing Development Office |