| ox | wół |
| Ox heart | Krowa |
| Ox tongue | Krowa |
| oxacyclopropane | tlenek etylenu |
| Oxalyl chloride | Chlorek oksalilu |
| Oxana Fedorova | Oksana Fiodorowa |
| Oxazole | Oksazol |
| oxbow lake | starorzecze |
| Oxelösund Municipality | Gmina Oxelösund |
| Oxer | Okser |
| Oxfam | Oxfam |
| Oxford | Oksford |
| Oxford County | Hrabstwo Oxford |
| Oxford English Dictionary | Oxford English Dictionary |
| Oxfordian | Oksford |
| Oxfordian stage | Oksford |
| Oxfordshire | Oxfordshire |
| Oxhide | Krowa |
| oxidation | utlenianie |
| Oxidation state | Stopień utlenienia |
| oxidation-reduction | utlenianie-redukcja |
| oxide | tlenek |
| oxidisable material | substancja utlenialna |
| oxidising agent | utleniacz |
| oxirane | tlenek etylenu |
| Oxonian | Oksford |
| Oxonium ion | Jon hydroniowy |
| Oxus | Amu-daria |
| Oxy-fuel welding and cutting | Palnik acetylenowo-tlenowy |
| Oxycodone | Oksykodon |
| oxygen | tlen |
| Oxygen Catastrophe | Katastrofa tlenowa |
| oxygen content | zawartość tlenu |
| Oxygen cylinder | Tlen |
| Oxygen difluoride | Difluorek tlenu |
| Oxygen sensor | Sonda lambda |
| Oxygen tank | Butla nurkowa |
| Oxygen therapy | Tlenoterapia |
| oxygenation | natlenianie |
| Oxygene | Oxygène |
| Oxyloma elegans | Bursztynka wysmukła |
| Oxymetazoline | Oksymetazolina |
| oxymoron | oksymoron |
| Oxyrhynchus | Oksyrynchos |
| Oxytocin | Oksytocyna |
| Oxyurinae | Sterniczki |
| Oy-Mittelberg | Oy-Mittelberg |
| Oyashio class submarine | Okręty podwodne typu Oyashio |
| Oyem | Oyem |
| Oymyakon | Ojmiakon |
| Oyneg Shabbos | Oneg Szabat |
| Oyo | Oyo |
| Oyo Empire | Oyo |
| Oyo State | Oyo |
| oyster | ostryga |
| oyster farming | hodowla ostryg |
| oystercatcher | ostrygojad |
| Oysters | Ostrygi |
| Oz | Oz |
| Ozimek | Ozimek |
