| opprobre | infamy |
| Oprah Winfrey | Oprah Winfrey |
| Oprichnik | Oprichnik |
| Opritchnina | Oprichnina |
| Ops | Ops |
| opter | choose |
| opter de | conclude |
| Opteron | Opteron |
| opticien | optician |
| opticienne | optician |
| optimal | optimal |
| optimaliser | optimize |
| Optimates | Optimates |
| Optimisation | Optimization |
| Optimisation combinatoire | Combinatorial optimization |
| Optimisation de code | Optimization |
| optimisation des installations | installation optimisation |
| optimiser | optimize |
| optimisme | optimism |
| optimiste | upbeat |
| Optimized link state routing protocol | Optimized Link State Routing protocol |
| optimum | optimum |
| Optimum de Pareto | Pareto efficiency |
| Optimus | Optimus keyboard |
| option | option |
| option d'achat | call |
| option de vente | put |
| option principale | major |
| option secondaire | minor |
| Option sur taux | Interest rate derivative |
| optique | approach |
