| Opi | grandfather |
| Opiat | opiate |
| Opium | opium |
| Opioid | opioid |
| Hopi | Hopi |
| Kopie | copy duplicate blueprint manifold replica replication print reprint |
| Anopie | anopia |
| Atopie | atopy |
| Kopiar | cartulary |
| Kopist | copyist |
| Kuopio | Kuopio |
| Mopila | morning wood |
| Propin | propyne |
| Doping | doping |
| Myopie | myopia |
| Utopia | utopia |
| Utopie | utopia |
| Woopie | woopie woopy |
| -skopie | -scopy |
| Copilot | copilot |