| Open Database Connectivity | ODBC |
| Open Directory Project | Open Directory Project |
| Open format | Formato aberto |
| open freight car | vagão |
| Open Game | Aberturas Abertas |
| Open Gaming License | Open Gaming License |
| open house | dia de visitação e inspeção |
| Open Innovation | Open Innovation |
| open lawn | relvados |
| Open mapping theorem | Teorema de Banach-Schauder |
| open noteng | corda solta (música) |
| open policylicy | apólice abertaro |
| Open problem | Lista de problemas em aberto |
| open railroad freight car | vagão |
| Open relationship | Casamento aberto |
| open sea | mar aberto |
| open sea fishing | pesca no mar alto |
| Open set | Conjunto aberto |
| Open source | Software livre |
| Open Source Definition | Licença de software livre |
| Open source movement | Software livre |
| Open source software | Software livre |
| open space | clareira |
| Open star cluste | Aglomerado estelar aberto |
| Open star cluster | Aglomerado estelar aberto |
| Open star clusters | Aglomerado estelar aberto |
| open the eyes | abrir os olhos de |
| Open University of Israel | Universidade Aberta de Israel |
| open up | abrir |
| Open wheel car | Monoposto |
| Open Your Heart | Open Your Heart |
| open-air | ao ar livre |
| open-ended | em aberto |
| open-eyed | com os olhos abertos |
| open-handed | mão-aberta |
| open-heart | de coração aberto |
| open-heart surgery | cirurgia de coração aberto |
| open-hearted | franco |
| Open-mid front unrounded vowel | Vogal anterior semiaberta não-arredondada |
| open-minded | liberal |
| open-mouthed | boquiaberto |
| open-pit mining | minas a céu aberto |
| open-plan office | escritório aberto |
| Open-source license | Licença de software livre |
| Open-source software | Software livre |
| Openbox | OpenBox |
| opencast mining | minas a céu aberto |
| OpenCms | OpenCMS |
| Opened and closed | Aberto e fechado |
| openene | aberto |
| openerash sketch | desencadeador |
| openeropener | abridorde garrafas |
| opening | início |
| Opening of the mouth ceremony | Abertura da boca |
| opening time | horário de abertura |
| openingnd | primeiro passo |
| OpenLaszlo | Laszlo |
| openly | francamente |
| openly declared | reconhecido |
| openly stated | aberto |
| OpenMosix | OpenMosix |
| Opennap | OpenNap |
| OpenSolaris | OpenSolaris |
| OpenStep | OpenStep |
| OpenSUSE | OpenSUSE |
| OpenTibia | OpenTibia |
| OpenVMS | OpenVMS |
| opera | ópera |
| Opera game | Partida da Ópera |
| opera houseic | teatro lírico |
| Opera Software | Opera Software |
| operable | realizável |
| Operación Triunfo | Operação Triunfo |
