| Owen | Owen |
| Owen Gun | Owen |
| Owen Willans Richardson | Owen Willans Richardson |
| Owen Wilson | Owen Wilson |
| Owensboro | Owensboro |
| Owerpass | Gateway |
| Owhyee | Owhyee |
| owing to | dovuto a |
| owing to someone | arretrato |
| Owingen | Owingen |
| owl | gufo |
| Owl Nebula | Nebulosa Gufo |
| owlet | civetta |
| owlish | da gufo |
| own | possedere |
| own goal | autorete |
| own weight | peso specifico |
| owner | titolare |
| Owner free filing system | Owner Free Filing System |
| owner of a shipping company | armatore |
| ownership | proprietà |
| Ownership equity | Capitale sociale |
| ox | bue |
| oxalate | ossalato |
| Oxalidaceae | Oxalidaceae |
| Oxalis acetosella | Oxalis |
| Oxalis corniculata | Oxalis corniculata |
| Oxalis pes-caprae | Oxalis pes-caprae |
| Oxalis stricta | Oxalis stricta |
| Oxazines | Oxazine |
| Oxelösund Municipality | Municipalità di Oxelösund |
| oxes | sgobbare |
| oxeye | margherita |
| oxeye daisy | margherita |
| Oxfam | Oxfam |
| Oxford | Oxford |
| Oxford English Dictionary | Oxford English Dictionary |
| Oxford Street | Oxford Street |
| Oxfordian stage | Oxford |
| Oxfordshire | Oxfordshire |
| oxidant | ossidante |
| oxidation | ossidazione |
| Oxidation state | Stato di ossidazione |
| oxidation-reduction | ossidoriduzione |
| Oxidative stress | Stress ossidativo |
| oxide | ossido |
| oxidisable material | sostanza ossidabile |
| oxidising agent | agente ossidante |
| oxidize | ossidare |
| Oxoacid | Ossiacidi |
| Oxprenolol | Oxprenololo |
| oxtail | coda di bue |
| Oxus | Amu Darya |
| Oxy-fuel welding and cutting | Saldatura ossiacetilenica |
| Oxyacetylene burner | Cannello ossiacetilenico |
| Oxycodone | Ossicodone |
| oxygen | ossigeno |
| Oxygen balance | Bilancio di ossigeno |
| oxygen content | contenuto in ossigeno |
| Oxygen cylinder | Ossigeno |
| Oxygen lance | Lancia termica |
| oxygen mask | maschera per l'ossigeno |
| oxygen tent | tenda a ossigeno |
| oxygenate | ossigenare |
| oxygenated | ossigenato |
| oxygenation | ossigenazione |
| Oxygene | Oxygene |
| Oxymoron | Ossimoro |
| Oxyrhynchus | Ossirinco |
| Oxytocin | Ossitocina |
| Oy | OY |
| Oy-Mittelberg | Oy-Mittelberg |
| Oya | Oyá |
| oyes | udite |
| oyez | udite |
| Oymapinar Dam | Oymapınar |
| Oymyakon | Ojmjakon |
| Oyo Empire | Oyo |
| Oyo State | Oyo |
| oyster | ostrica |
| oyster farming | ostricoltura |
| oystercatcher | beccaccia di mare |
| Oysters | Ostrea |
| Oyón | Oyón |
| Oyón-Oion | Oyón |
| Oz | OZ |
| Oza dos Ríos | Oza dos Ríos |
| Ozamiz City | Ozamiz |
| ozeanic | oceanico |
