| Term | Definition | Contributor | Modified |
|---|---|---|---|
| o2minus | No definition provided | Ryan McGranaghan | 2023.04.16 |
| o3 | A nearly colorless gas, it is a very strong absorber of ultraviolet radiation, and the presence of the ozone layer in the upper atmosphere provides an ozone shield that prevents dangerous radiation fr om reaching the earth's surface. | Ryan McGranaghan | 2023.04.16 |
| o3minus | No definition provided | Ryan McGranaghan | 2023.04.16 |
| o3minusminus | No definition provided | Ryan McGranaghan | 2023.04.16 |
| o4 | No definition provided | Ryan McGranaghan | 2023.04.16 |
| o5 | No definition provided | Ryan McGranaghan | 2023.04.16 |
| OACT__HALPH | No definition provided | Ryan McGranaghan | 2023.04.16 |
| Oak | No definition provided | Christopher Rauch | 2023.12.01 |
| Oases | No definition provided | Christopher Rauch | 2023.12.01 |
| O associations | No definition provided | Ryan McGranaghan | 2023.04.16 |
| Oaths | No definition provided | Christopher Rauch | 2023.12.01 |
| Oatmeal | No definition provided | Christopher Rauch | 2023.12.01 |
| Oats | No definition provided | Christopher Rauch | 2023.12.01 |
| OB associations | A loosely bound grouping of O and B stars that typically stretches up to several hundred light-years and may contain between a dozen and several hundred O stars and B stars. The members of an OB assoc iation are young and of roughly the same age. OB associations dissipate in a few tens of millions of years. | Ryan McGranaghan | 2023.04.16 |
| Obduction tectonics | No definition provided | Ryan McGranaghan | 2023.04.16 |
| Obedience | No definition provided | Christopher Rauch | 2023.12.01 |
| Obelisks | No definition provided | Christopher Rauch | 2023.12.01 |
| Oberon | The second-largest and second most massivemon of Uranus, and the ninth most massive moon in the Solar System. | Ryan McGranaghan | 2023.04.16 |
| Obertiite | No definition provided | Ryan McGranaghan | 2023.04.16 |
| obervation | No definition provided | Ryan McGranaghan | 2023.04.16 |