| racquetball | racquetball |
| Rad | RAD |
| Rada Suprema | Verkhovna Rada |
| Radagaiso | Radagaisus |
| Radagast el Pardo | Radagast |
| Radama I | Radama I of Madagascar |
| Radamanthys de Wyvern | Wyvern Rhadamanthys |
| Radamanto | Rhadamanthus |
| radar | radar |
| Radar de apertura sintética | Synthetic aperture radar |
| Radar de tráfico | Road-rule enforcement camera |
| Radar óptico | Optical radar |
| Radclyffe Hall | Radclyffe Hall |
| Radeberg | Radeberg |
| Radebeul | Radebeul |
| Radelfingen | Radelfingen |
| Radelgar de Benevento | Radelgar of Benevento |
| Radeon | Radeon |
| Radermachera sinica | Radermachera sinica |
| Radeče | Radeče |
| Radha | Radha |
| Radha Mitchell | Radha Mitchell |
| Radi Nedelchev | Radi Nedelchev |
| radiacion | radiance |
| radiación | radiation |
| radiación alfa | alpha radiation |
| Radiación atmosférica | Atmospheric radiation |
| radiación beta | beta radiation |
| Radiación ciclotrón | Cyclotron radiation |
| radiación cósmica | cosmic radiation |
| Radiación de Cherenkov | Cerenkov effect |
| Radiación de cuerpo negro | Black body radiation |
| radiación de fondo | background radiation |
| Radiación de fondo de microondas | Cosmic microwave background radiation |
| Radiación de Hawking | Hawking radiation |
| Radiación del cielo | Sky radiation |
| Radiación del continuo | Continuum radiation |
| Radiación difusa | Diffuse radiation |
| Radiación electromagnética | Electromagnetic radiation |
| radiación gamma | gamma radiation |
| radiación infrarroja | infrared radiation |
| Radiación infrarrojo próximo | Near infrared radiation |
| radiación ionizante | ionising radiation |
| Radiación libre-libre | Free-free emission |
| radiación no ionizante | non-ionising radiation |
| Radiación no térmica | Nonthermal radiation |
| Radiación nuclear | Nuclear radiation |
| Radiación sincrotron | Synchrotron radiation |
| Radiación sincrotrón | Gyrosynchrotron radiation |
| radiación solar | solar radiation |
| Radiación terrestre | Terrestrial radiation |
| radiación ultravioleta | ultraviolet radiation |
| Radiación UV lejana | Far ultraviolet radiation |
| Radiación UV próxima | Near ultraviolet radiation |
| Radiación X | X ray radiation |
| radiactividad | radioactivity |
| radiactividad natural | natural radioactivity |
| radiactivo | radioactive |
| radiacíon | radiation |
| radiador | radiator |
| radiador eléctrico | electric heater |
| radial | radial |
