| ottuagenario | Achtzigjährige |
| otturamento | Überfüllen |
| otturare | abdichten |
| otturatore | Verschluss |
| otturazione | Füllung |
| ottuso | stumpf |
| Ottweiler | Ottweiler |
| Otus scops | Zwergohreule |
| Otzberg | Otzberg |
| Otzing | Otzing |
| OU | OU |
| Ouaddaï | Wadai |
| Ouagadougou | Ouagadougou |
| Ouarzazate | Ouarzazate |
| Oud | Oud |
| Oudenaarde | Oudenaarde |
| Oudomxay | Oudomxay |
| Oudtshoorn | Oudtshoorn |
| Ouessant | Ouessant |
| Ouest | Westen |
| Ouest Department | Ouest |
| Ouguiya mauritana | Ouguiya |
| OUI | Ja |
| Oulainen | Oulainen |
| Oulens-sous-Echallens | Oulens-sous-Echallens VD |
| Oulens-sur-Lucens | Oulens-sur-Lucens VD |
| Oulipo | Oulipo |
| Oullins | Oullins |
| Oulu | Oulu |
| Oulujoki | Oulujoki |
| Oulujärvi | Oulujärvi |
| Oulun | Oulun |
| Oulunsalo | Oulunsalo |
| OUR | Our |
| Our Love to Admire | Our Love To Admire |
| Ouranosaurus nigeriensis | Ouranosaurus |
| Ourebia ourebi | Bleichböckchen |
| Ourengoï | Gasfeld Urengoi |
| Ourense | Ourense |
| Ourique | Ourique |
| Ourne Valley | Ourne Valley |
| Ouro Preto | Ouro Preto |
| Ourscamp | Ourscamp |
| Ousmane Sembène | Ousmane Sembène |
| Out of Sight | Out of Sight |
| Outburst | Ausbrueche |
| Outer Skerries | Out Skerries |
| Outing | Outing |
| OutKast | OutKast |
| Outlawz | Outlawz |
| Outliner | Gliederungseditor |
| Outlook Express | Outlook Express |
| Outokumpu | Outokumpu |
| output | Ausgabe |
| Outremer | Outremer |
| Outside | Äußere |
| outsider | Außenseiter |
| Outsourcing | Outsourcing |
| ouverture | Ouvertüre |
| Ouviram do Ipiranga às margens plácidas | Hino Nacional Brasileiro |
| Ouyang Xiu | Ouyang Xiu |
| ouzo | Ouzo |
| Ouémé | Ouémé |
| OV | OV |
| ovaia | Eierstock |
| ovaio | Eierstock |
| ovale | oval |
| Ovale di Cassini | Cassinische Kurve |
| Ovambo | Ovambo |
| Ovanåker | Ovanåker |
| Ovar | Ovar |
| ovarica | ovarial |
| ovarico | Eierstock- |
| ovariectomia | sterilisieren |
| ovario | Eierstock |
| ovatta | Watte |
| ovattare | füttern |
| ovazione | begeisterter Beifall |
| Over the Hills and Far Away | Over the Hills and Far Away |
| Over the Rainbow | Over the Rainbow |
| Over the Top | Over the Top |
| Overbooking | Überbuchung |
| Overclocking | Übertakten |
| Overdose | Überdosis |
| Overdrive | Overdrive |
| Overfishing | Überfischung |
| Overfitting | Überanpassung |
| Overflow | Arithmetischer Überlauf |
| Overhead | Overhead |
| Overijssel | Overijssel |
| Overture | Ouvertüre |
| Overwrite | Wand |
| Overijssel | Overijssel |
| ovest | Westen |
