| 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&CC | Recorder And Communication Control | - | Organizations |
| R&D | Research And Development | - | Organizations |
| R&DO | Research And Development Operations (MSFC) | - | Organizations |
| R&OA | Reliability And Quality Assurance | - | Organizations |
| R&P | Reserve And Process | - | Organizations |
| R&PM | Research And Program Management | - | Organizations |
| R&R | Remove And Replace | - | Organizations |
| R&R | Rendezvous And Recovery | - | Organizations |
| R&Z | Range And Zero | - | Organizations |
| R-T | Resistance Test | - | Organizations |
| R/A | Radar Altimeter | - | Organizations |
| R/C | Radio Command | - | Organizations |
| R/C | Rate Of Climb | - | Organizations |
| R/C | Remote Control | - | Organizations |
| R/D | Rate Of Descent | - | Organizations |
| R/E | Reentry | - | Organizations |
| R/I | Receiving Inspection | - | Organizations |
| R/L | Rate/Limited | - | Organizations |
| R/L | Remote/Local | - | Organizations |
| R/O | Rollout | - | Organizations |
| R/S | Range Safety | - | Organizations |
| R/S | RedundantSet | - | Organizations |
| R/T | Real Time | - | Organizations |
| R/T | Receiver/Transmitter | - | Organizations |
| R/W | Read/Write | - | Organizations |
| R/W | Runway | - | Organizations |
| RA | Radar Altimeter | - | Organizations |
| RA | Radar Altimeter (R/A Preferred) | - | Organizations |
| RA | Radium | - | Organizations |
| RA | Range Area | - | Organizations |
| RA | Right Aft | - | Organizations |
| RA | Right Ascension | - | Organizations |
| RAAB | Remote Amplifier Acquisition And Advisory Box | - | Organizations |
| RAAB | Remote Amplifier And Adoption Box | - | Organizations |
| RAAB | Remote Application And Advisory Box | - | Organizations |
| RAC | ReliabilitY Action Center | - | Organizations |
| RACS | Rotation Axis Coordin | - | Organizations |
| RACS | Remote Automatic Calibration System | - | Organizations |
| RACU | Remote Acquisition And Command Unit | - | Organizations |
| RAD | Radar | - | Organizations |
| RAD | Radian | - | Organizations |
| RAD | Radiation Dosage | - | Organizations |
| RAD | Radiation Equivalent Dose | - | Organizations |
| RAD | Radius | - | Organizations |
| RAD | Roentgen Absorbed Dosage | - | Organizations |
| RADAR | Radio Detecting And Ranging | - | Organizations |
| RADCC | Radiation Control Center | - | Organizations |
| RAE | Radio Astronomy Explorer | - | Organizations |
| RAF | Requirements Analysis Form | - | Organizations |
| RAG | Reusable Agenda | - | Organizations |
| RAHF | Research Animal Holding Facility | - | Organizations |
| RAI | Radar Altimeter Indicator | - | Organizations |
| RAI | Rofl Attitude Indicator | - | Organizations |
| RAL | ResPonsibiiitV Aslignment List | - | Organizations |
| RALPH | Reduction And Acquisition Of Lunar Pulse Heights | - | Organizations |
| RALT | Radar Altimeter | - | Organizations |
| RAM | Radar Absorption Material | - | Organizations |
| RAM | Random Access Memory | - | Organizations |
| RAM | Random-access Memory | - | Organizations |
| RAM | Research And Applications Module | - | Organizations |
| RAM | Responsibility Assignment Matrix | - | Organizations |
| RAMA | Recap And Movement Authorization | - | Organizations |
| RANC | Radar Absorption Noise And Clutter | - | Organizations |
| RANN | Research Applied To National Needs | - | Organizations |
| RAPCON | Radar Approach And Control | - | Organizations |
| RAPS | Right AFT Propulsion System | - | Organizations |
| RAS | Requirements Allocation Sheet | - | Organizations |
| RATCC | Radar Air Traffic Control Center | - | Organizations |
| RAU | Remote Acquisition Unit | - | Organizations |
| RAU | Remote Acquisition Unit | - | Organizations |
| RAUIS | Remote Acquisition Unit Interconnecting Station | - | Organizations |
| RAX | Remote Access Computing System | - | Organizations |
| RAX | Remote Access Terminal | - | Organizations |
| RB | Radar Beacon | - | Organizations |
| RBA | Radar Beacon Antenna | - | Organizations |
