| Abbreviation | Definition |
|---|---|
| HMS | History Memory System |
| HMU | Hardware Mockup |
| HMV | Hydrogen Manual Valve |
| HNAV | Horizontal Navigation |
| HNDLER | Handler |
| HNGR | HaNGaR |
| HO | Hydrogen-Oxygen |
| HOI | Halo Orbit Insertion |
| HOLC | High Order Language Computer |
| HOP | Halo Orbit Phase |
| HORIZ | HORIZon |
| HOS | High Order Software |
| HOS | High-Order Software |
| HOSC | Huntsville Operations Support Center |
| HP | Handling Procedure |
| HP | Heat Pipe |
| HP | Height of Perigee |
| HP | Hewlett Packard |
| HP | High Pressure |
| HP | Hydrogen Purge |