| Opatovce | Opatovce |
| Opatovce nad Nitrou | Opatovce nad Nitrou |
| Opava | Opava |
| Opava District | Distretto di Opava |
| Opava River | Opava |
| OPEC | OPEC |
| Opel | Opel |
| Opel Antara | Opel Antara |
| Opel Astra | Opel Astra |
| Opel Corsa | Opel Corsa |
| Opel Kadett | Opel Kadett |
| Opel Meriva | Opel Meriva |
| Opel Vectra | Opel Vectra |
| Opel Zafira | Opel Zafira |
| open | sincero |
| open again | riaprire |
| Open and closed maps | Funzione aperta |
| Open bog | Neva |
| Open city | Città aperta |
| Open cluster | Ammasso aperto |
| Open content | Open content |
| Open Database Connectivity | ODBC |
| Open Directory Project | Open Directory Project |
| Open dump | Mondezzaio |
| open eyed | con gli occhi spalancati |
| Open field system | Campi aperti |
| open fire | fuoco nel caminetto |
| Open format | Formato aperto |
| open freight car | pianale |
| Open Gaming License | Open Gaming License |
| open handed | liberale |
| Open hearth furnace | Forno Martin-Siemens |
| open house | giorno di ricevimento |
| Open into | Sboccare in |
| open lawn | prato coltivato |
| Open mapping theorem | Teorema della funzione aperta |
| Open Network Computing Remote Procedure Call | ONC RPC |
| Open on to | Affacciarsi su |
| open railroad freight car | pianale |
| Open reading frame | Open reading frame |
| open sea | largo |
| open sea fishing | pesca d'altura |
| Open set | Insieme aperto |
| Open Sound System | Open Sound System |
| Open source | Opensource |
| Open Source Definition | Open Source Definition |
| Open Source Development Labs | OSDL |
| Open Source Intelligence | OSINT |
| Open source movement | Opensource |
| Open source religion | Yoismo |
| Open source software | Opensource |
| open space | spazio aperto |
| Open Space Technology | Open Space Technology |
| Open spectrum | Open Spectrum |
| Open star cluste | Ammasso aperto |
| Open star cluster | Ammasso aperto |
| Open star clusters | Ammassi aperti |
| Open straight out into | Affacciarsi su |
| open the eyes | disingannare |
| Open universe | Universo aperto |
| Open Your Eyes | Open Your Eyes |
| Open Your Heart | Open Your Heart |
| open-air | all'aperto |
| open-air dance-hall | balera |
| open-ended | senza limiti precisi |
| open-eyed | con gli occhi spalancati |
| open-handed | liberale |
| open-heart | a cuore aperto |
| open-heart surgery | chirurgia a cuore aperto |
| open-hearted | sincero |
| open-minded | di larghe vedute |
| open-pit mining | attività mineraria a cielo aperto |
| open-plan office | ufficio con divisori |
| Open-source license | Licenza open source |
| Open-source software | Opensource |
| OpenArena | OpenArena |
| opencast mining | attività mineraria a cielo aperto |
| OpenCD | TheOpenCD |
| OpenCms | OpenCms |
| OpenDocument Format Alliance | OpenDocument Format Alliance |
| opened | aperto |
| opened wide | spalancato |
| opener | apriscatole |
| openers | apriscatola |
| openhanded | liberale |
| opening | apertura |
| opening time | orario d'apertura |
| OpenLaszlo | OpenLaszlo |
| openly | francamente |
| openly declared | dichiarato |
| openly stated | dichiarato |
| OpenMosix | OpenMosix |
| Opennap | OpenNap |
| openness | franchezza |
| opens | apre |
| OpenSolaris | OpenSolaris |
| OpenSUSE | OpenSUSE |
| OpenUP | Open Unified Process |
| OpenVMS | OpenVMS |
| OpenVPN | OpenVPN |
| Openwor | Graticolat |
| OpenWrt | OpenWRT |
| opera | opera |
