| oindrivbar | irrecoverable |
| oinlösbar | irredeemable |
| oinlöslig | irredeemable |
| Oinomaos | Oenomaus |
| Oinone | Oenone |
| Oinopion | Oenopion |
| oinskränkt | unrestricted |
| oinspirerad | dull |
| oinspirerande | stale |
| ointaglig | impregnable |
| ointressant | stale |
| ointresserad | disinterested |
| ointresserat | apathetically |
| oinvigd | uninitiated |
| Oireachtas | Oireachtas |
| Oise | Oise |
| Oita prefektur | Ōita Prefecture |
| Oita Trinita | Oita Trinita |
| oj | ouch |
| oj! | ouch |
| Ojibwa | Ojibwa |
| Ojin | Emperor Ōjin |
| Ojmjakon | Oymyakon |
| Ojos del Salado | Ojos del Salado |
| ojust | foul |
| ojust spel | foul play |
| ojämförbar | incommensurable |
| ojämförlig | incomparable |
| ojämn | rough |
| ojämt | unevenly |
| ojäst | unleavened |
| ojävig | disinterested |
| ok | yoke |
| OK Go | OK Go |
| OK-jolle | OK |
| okammad | untidy |
| okapi | okapi |
| Okapi viltreservat | Okapi Wildlife Reserve |
| okarina | ocarina |
| Okayama prefektur | Okayama Prefecture |
| okben | cheekbone |
| Okcheon | Okcheon County |
| Okeanider | Oceanid |
| Okeanos | Ocean |
| Okefenokee | Okefenokee Swamp |
| Okeh | Okeh Records |
| okej | all right |
| Okhimos | Ochimus |
| Okinawa | Okinawa Island |
| Okinawa prefektur | Okinawa Prefecture |
| Oklahoma | Oklahoma |
| Oklahoma City | Oklahoma City |
| Oklahomas flagga | Flag of Oklahoma |
| oklanderlig | perfect |
| oklanderligt | flawlessly |
| oklar | dim |
| oklarhet | duskiness |
| oklart | obscure |
| oklippt | uncut |
| Oklo | Oklo |
| oklok | foolish |
| oklokhet | indiscretion |
| okokt | raw |
| okomplicerad | simple |
| okomprimerad | unpacked |
| okomprimerade | uncompressed |
| Okonomiyaki | Okonomiyaki |
| okonstlad | natural |
| okonstnärlig | inartistic |
| okontrollerad | unbridled |
| okontrollerat | uncontrollably |
| okontrollerat utsläpp av organismer | accidental release of organisms |
| okontrollerbar | uncontrollable |
| okontrollerbart | uncontrollably |
| okonventionell | unconventional |
| okonventionellt | unconventionally |
| okra | okra |
| okritisk | uncritical |
| okroppslig | immaterial |
| okrossbar | unbreakable |
| okränkbar | sacrosanct |
| okränkbarhet | inviolability |
| okränkt | inviolate |
| Oksana Akinsjina | Oksana Akinshina |
| Oktala talsystemet | Octal |
| Oktalt | Octal |
| oktan | octane |
| Oktanten | Octans |
| oktav | octavo |
| oktavformat | octavo |
| oktett | octet |
| Oktettregeln | Octet rule |
| oktober | October |
| Oktoberfest | Oktoberfest |
| Oktoberkriget | Yom Kippur War |
| Oktoberrevolutionen | October Revolution |
| Oktoberstormhatt | Aconitum carmichaelii |
| oktogon | octagon |
| Oktonion | Octonion |
| Okubo Toshimichi | Ōkubo Toshimichi |
| okular | ocular |
| okultiverad | savage |
| okulär | ocular |
| Okuma Shigenobu | Ōkuma Shigenobu |
| okunnig | unenlightened |
