| Optimum | optimum |
| Optimat | optimate |
| optimal | optimal optimum |
| Aptium | Aptian |
| Optik | optics |
| Optiker | optician |
| Optimist | optimist |
| Option | option |
| optisch | optic optical |
| Infimum | infimum |
| Maximum | maximum |
| Minimum | minimum |
| Koptin | Copt |
| Koptisch | Coptic |
| koptisch | Coptic |
| Optode | optode |
| Optativ | optative optative mood |
| Optimatin | optimate |
| Optimismus | optimism |
| Panoptikum | wax museum |