| obdachlos / Obdachlose (m) | homeless |
| obere Hanglage (f) | upslope |
| oberes Stockwerk (n) | upper floor |
| Oberfläche (f) | surface |
| Obergeschoss (n) | top floor / upper floor |
| Objektförderung (f) | building subsidy |
| Obligation (f) | bond / certificate of debt / debenture |
| Obligo (n) | exposure (fin) / commitment / liabilities |
| Obligoausnutzung (f) | use of credit line (partial / full) |
| Ofen (m) | stove / oven |
| offene Handelsgesellschaft (f) (OHG) | general (ordinary) partnership |
| öffentlich | public |
| öffentlich-rechtlich | under public law |
| Öffentliche Ausschreibungen (pl) der EU (Bekantgabe durch OJEU - official journal of the European Union) | public tenders: OJEU (official journal of the European Union) procedures - process by which major works are tendered in the EU |
| öffentliche Finanzierung (f) | public financing |
| öffentliche Hand (f) | public authorities / state |
| öffentliche(n) Verkehrsmittel (n/pl) | public transport |
| Öffentlichkeitsarbeit (f) | public relations |
| Ökologie (f) | ecology |
| Ölheizung (f) | oil heating |
| Opportunitätskosten (pl) | opportunity costs / alternative costs |
| Option (f) auf vorzeitige Vertragsbeendigung/Rückzahlung | break option / early repayment option (ERP) |
| Optionsschein (m) | warrant |
| ordentlich | tidy / neat |
| Organgesellschaft (f) | consolidated company / controlled company |
| Organigramm (n) | organizational chart |
| Organisation (f) | organization |
| Ort (m) | location / place / site |
| Ortsbehörde (f) | local authority |
| Ortsbild (n) | view of a place / appearance of a town |
| ostseitig / nach O. gerichtet | east-facing / eastbound |