| Abbreviation | Definition |
|---|---|
| HCSI | Hughes Communications Services, Inc. |
| HCSL | Hybrid Computation and Simulation Laboratory |
| HCU | Hydraulic Charging Unit |
| HCV | Hydrogen Check Valve |
| HD | Heavy Duty |
| HD | High Drag |
| HD | Highly Desirable |
| HD | HoldDown |
| HD | Horizontal Drain |
| HD | Hydrogen Drain |
| HDA | Housekeeping Data Acquisition |
| HDC | Hasselblad Data Camera |
| HDC | Hybrid Device Controller |
| HDDR | High-Density Digital Recorder |
| HDG | HeaDinG |
| HDP | HoldDown Post |
| HDQ | HeaDQuarters |
| HDR | Hardware Design Review |
| HDR | High Data Rate |
| HDRA | High Data Rate Assembly |