| Abbreviation | Definition |
|---|---|
| R10 | Radial Road 10 (Manila, Philippines) |
| R21 | Renault 21 |
| RA | Retard Advance |
| RA | Route Advertisement |
| RA | Routing Area |
| RAA | Regional Airline Association |
| RABIT | Robotics Assisted Bridge Inspection Tool |
| RAC | Reservation Against Cancellation |
| RAD | Readily Available Deliveries |
| RAD | Robot Assisted Delivery |
| RAD | Route Availability Document |
| RADNAV | Radio Navigation |
| RAF | Road Accident Fund |
| RAF | Royal Air Flight |
| RAHX | Ram Air Heat Exchanger |
| RAID | Remove Alcohol Impaired Drivers |
| RAIL | Runway Alignment Indicator Lights |
| RAIN | Riverdweller's Aid Innercity Network |
| RAIRS | Railroad Accident / Incident Reporting System |
| RAISE | Rebuilding American Infrastructure with Sustainability and Equity |