| Term | Definition | Contributor | Modified |
|---|---|---|---|
| Rhynchota | No definition provided | Christopher Rauch | 2023.12.01 |
| rhyolite | Volcanic rock (or lava) that characteristically is light in color, contains 69% silica or more, and is rich in potassium and sodium. | Ryan McGranaghan | 2023.04.16 |
| Rhyolite | No definition provided | Christopher Rauch | 2023.12.01 |
| Rhythm | No definition provided | Christopher Rauch | 2023.12.01 |
| RI | The international standard relative sunspot number. | Ryan McGranaghan | 2023.04.16 |
| Ribbeite | No definition provided | Ryan McGranaghan | 2023.04.16 |
| Ribs | No definition provided | Christopher Rauch | 2023.12.01 |
| Ribs--Abnormities and deformities | No definition provided | Christopher Rauch | 2023.12.01 |
| Rice | No definition provided | Christopher Rauch | 2023.12.01 |
| Rice and rice culture | No definition provided | Christopher Rauch | 2023.12.01 |
| Rice--Bacteriology | No definition provided | Christopher Rauch | 2023.12.01 |
| Rice beer | No definition provided | Christopher Rauch | 2023.12.01 |
| Rice, Wild | No definition provided | Christopher Rauch | 2023.12.01 |
| Rice-wine | No definition provided | Christopher Rauch | 2023.12.01 |
| richardson number | No definition provided | Ryan McGranaghan | 2023.04.16 |
| Richellite | No definition provided | Ryan McGranaghan | 2023.04.16 |
| Richelsdorfite | No definition provided | Ryan McGranaghan | 2023.04.16 |
| Riches | No definition provided | Christopher Rauch | 2023.12.01 |
| Richetite | No definition provided | Ryan McGranaghan | 2023.04.16 |
| Rich galaxy clusters | A galaxy cluster with a particularly large number of galaxies. | Ryan McGranaghan | 2023.04.16 |