| R | Gas Constant | - | Organizations |
| R | Radius | - | Organizations |
| R | Range | - | Organizations |
| R | Range Rate | - | Organizations |
| R | Rankine | - | Organizations |
| R | Ratio | - | Organizations |
| R | Rear | - | Organizations |
| R | Receive | - | Organizations |
| R | Redundant | - | Organizations |
| R | Regulate | - | Organizations |
| R | Rehydratable | - | Organizations |
| R | Reliability | - | Organizations |
| R | Replace | - | Organizations |
| R | Resistance | - | Organizations |
| R | Right | - | Organizations |
| R | Roentgen | - | Organizations |
| R | Roll | - | Organizations |
| R | Yaw Rankine Rate | - | Organizations |
| R | LEO Request Liaison Engineering Order | - | Organizations |
| R | LSS Regenerative Life Support System | - | Organizations |
| R | BARRadius Vector Axis | - | Organizations |
| R | DOTRange Rate To Target | - | Organizations |
| R | ETSReconfigurable Electrical Test Stand | - | Organizations |
| R | ETSReconfiguration Electrical Test Stand | - | Organizations |
| R | IMPMinimum Range To Avoid Plum Impingement | - | Organizations |
| R | Are | - | ISO Country Codes |
| R | Reinforcing - Right -R?ntgen | - | Astronomy |
| R | Rayleigh | - | Business and Finance |
| R | Roentger | - | Business and Finance |
