| Abbreviation | Definition |
|---|---|
| RTT | Round Trip Time |
| RTTR | Real Time Thermal Rating |
| RV | Radial Velocity |
| RV | Reference Value |
| RVR | Reactor Vessel Rupture |
| RVST | Resonance Vibrating Screening Technology |
| RW | Reverse Well |
| RWB | Recirculating Walking Beam |
| RWFVS | Reduced Wavelet Feature Vectors |
| RXF | Refracted X-ray Fluorescence |
| RXS | Resonant X-ray Scattering |
| S | Short |
| S | Spectro |
| S | Squarely |
| SA | Small Area |
| SA | Spatial Analysis |
| SAFE | Simulated Atomic Fission Engine |
| SAFT | Statistical Associating Fluid Theory |
| SAIP | South African Institute of Physics |
| SAM | Square Aperture Matrix |