| Ob (town) | Oba | OBAFGKM |
| Obal | Obal (estadyo) | Obalo |
| Obama | Obama, Fukui | Obama, Pukui |
| Obanasawa, Yamagata | Obanazawa | Obanazawa, Yamagata |
| Obandeño | Obandenio | Obandeno |
| Obandenyo | Obando | Obando (paglilinaw) |
| Obando (Valle del Cauca) | Obando Bulacan | Obando Bulakan |
| Obando Dance | Obando Fertility Rites | Obando, Bulacan |
| Obando, Bulakan | Obaryo | Obaryo ng alimango |
| Obaryo ng hayop-dagat | Obaryo ng hipon | Obaryo ng isda |
| Obaryo ng salungo | Obaryo ng sugpo | Obaryo ng tipay |
| Obaryo ng ulang | Obata no Onīsan | Obdaksion |
| Obdaksiyon | Obdaksyon | Obduction |
| Obduksion | Obduksiyon | Obduksyon |
| Obedience plant | Obena | Obenas |
| Obento | Ober Da Bakod | Oberbaumbrücke |
| Obere Warnow | Obes | Obesa |
| Obese | Obesidad | Obesiti |
| Obesity | Obeso | Obeyd |
| Obeyd-e Zakani | Obeyd-e Zākāni | Obeyde Zakani |
| Obeyde Zâkâni | Obhektibo | Obhektong oryented na pagpoprograma |
| Obhetibo | Obheto | Obi-Wan Kenobi |
| Obihiro | Obihiro, Hokkaidō | Obihiro, Hokkaido |
| Obis | Obispo | Obispo (ahedres) |
| Obispo (paglilinaw) | Obispo (pari) | Obispo (Simbahang Katolika) |
| Obispo (Simbahang Katoliko) | Obispo ng Alexandria | Obispo ng Altamura-Gravina-Acquaviva delle Fonti |
| Obispo ng Antioch | Obispo ng Roma | Obispo ng Romano |
| Obispong emeritus ng Roma | Obispong Kardenal | Obispong Kardinal |
| Obispong Romano | Obispong supragano | Obituary |
| Obituwaryo | Obitwaryo | Obitwaryo sa pahayagan |
| Object | Objective | Oblast |
| Oblast ng Kalininggrado | Oblast ng Kaliningrad | Oblast ng Moskow |
| Oblast ng Nagorno-Karabakh na Awtonomo | Oblast ng Nagorno-Karabakh na May Awtonomiya | Oblast ng Nagorno-Karabakh na Mayroong Awtonomiya |
| Oblasts of Russia | Oblasyon ng UP | Oblates of Saint Joseph College of Philosophy |
| Oblation run | Obligasyong moral | Oblong |
| Obluchye | Obninsk | Oborona Sevastopolya |
| Oboyan | Obra | Obra Maestra ng Pasalita at Di-nasasalat na Pamana ng Sangkatauhan |
| Obrero | Obscene | Obscenity |
| Obsenidad | Obserbador | Obserbahan |
| Obserbasyon | Obserbatoryo | Obserbatoryo ng La Silla |
| Obserbatoryo ng Lick | Obserbatoryong Astropisikal ng Crimea | Obserbatoryong Batikano |
| Obserbatoryong Pang-astropisika ng Crimea | Obserbatoryong Yerkes | Observant |
| Observatories | Observatory | Observe |
| Observer | Obsessive–compulsive disorder | Obsidian |
| Obsidiyano | Obstacle racing sa Palaro ng Timog Silangang Asya 2019 | Obstetrics and Gynecology Doctors |
| Obstipation | Obu, Aitsi | Obuladevaracheruvu |
| Obulasyon | Obulavaripalle mandal | Obum |
| Obuse, Nagano | OC-ute | Ocaña, Norte de Santander |
| Ocamonte | Ocampo | Ocampo Street |
| Ocampo, Camarines Sur | Occhieppo Inferiore | Occhieppo Superiore |
| Occhiobello | Occident | Occidental |
| Occidental Mindoro | Occidental Mindoro National College | Occidental Mindoro State College |
| Occidental Negros | Occimiano | Occipital lobe |
| Occipital lobes | Occupation | Ocean |
| Ocean exploration | Ocean god | Ocean Rain |
| Ocean science | Oceania | Oceanic |
| Oceanic science | Oceanography | Oceanology |
| Oceanside, California | Oceanus | Ochi, Kōchi |
| Ochlocracy | Ochodaeidae | Ochre |
| Ochyor | Ocicat | Ocimum basilicum |
| OCLC | OCLC (identifier) | Ocozias ng Israel |
| Ocozias ng Juda | OCR-A | OCR-B |
| Ocre | Octane | Octave Mirbeau |
| Octavian | Octaviano | Octavianus |
| Octavianus Augustus | Octavina | Octavina filipina |
| Octavina pilipina | Octavio Augusto | Octoarts Records |
| October | October (pelikula) | October 21 |
| October 4 | Octopi | Octopoda |
| Octopus | Octopus (paglilinaw) | Octopus vulgaris |
| Octopuses | Oculesics | Oculomotor nucleus |
| OCute | Ocute | Oda |
| Oda Nobunaga | Oda, Shimane | Oda, Syimane |
| Odai, Mie | Odalengo Grande | Odalengo Piccolo |
| Odate, Akita | Odawara | Odawara, Kanagawa |
| Odísia | Odússeia | ODD |
| Odd number | Odd-toed ungulate | Oddity |
| Ode | Ode to Joy | Odell illinois |
| Oden | Odeno | Odenthalius |
| Odenthalius de Robespierre | Odenthalius Isidore de Robespierre | Odenthalius Isidore Robespierre |
| Odenthalius Robespierre | Oderzo | Odesea |
| Odessa | Odette | Odia language |
| Odin | Odino | Odintsovo |
| Odiongan | Odiongan, Romblon | Odipo |
| Odipos | Odipus | Odisea |
| Odiseia | Odiseya | Odisha |
| Odisi | Odisia | Oditibong sistema |
| Oditoryong sistema | Odoacer | Odoacro |
| Odoakro | Odobakar | Odobenus |
| Odobenus rosmarus | Odolo | Odonata |
| Odontoceti | Odovacar | Odovakar |
| Odusea | Oduseia | Oduseya |
| Odusseia | Odyiya, Niigata | Odysea |
| Odysey | Odyssée | Odyssea |
| Odyssee | Odyssey | OEA |
| OED | Oedalechilus | Oedema |
| Oedipus | Oedipus complex | Oedipus conflict |
| Oesaphagus | Oesterreich | Oestreidae |
| Of Mice and Men | Ofakim | Ofena |
| Off The Record | Off! (tatak) | Off-shore hake |
| Offagna | Offering | Offerings |
