| Acronym | Definition |
|---|
| HCO | Html Converter |
| HCO | Harvard College Observatory |
| HCO | Hearing Carry-Over |
| HCO | Hubbard Communications Office (Scientology) |
| HCO | Health Care Organization |
| HCO | Hydraulic Clearance Optimization (gas turbine technology; Siemens) |
| HCO | Health Care Ombudsman (Vermont) |
| HCO | Honor Code Office (Brigham Young University; Utah) |
| HCO | Heavy Cycle Oil |
| HCO | Human Capital Office (various companies and government agencies) |
| HCO | Hollister Company (clothing line) |
| HCO | Human Capital Officer |
| HCO | Helicopter Control Officer |
| HCO | Hierarchical Cycloid Overlay (algorithms) |
| HCO | Head of Contracting Office |
| HCO | Health Care Officer |
| HCO | Heights Chamber Orchestra (Cleveland Heights, OH) |
| HCO | HC Orsteds Institute (Copenhagen, Denmark) |