| 奥斯曼帝国 | Ào sī màn dì guó | the Ottoman empire |
| 奥斯汀 | Ào sī tīng | Austin or Austen (name); Austin, Texas |
| 奥斯瓦尔德 | Ào sī wǎ ěr dé | Oswald |
| 奥斯陆 | Ào sī lù | Oslo, capital of Norway |
| 奥林匹亚 | Ào lín pǐ yà | Olympia (Greece) |
| 奥林匹克 | Ào lín pǐ kè | Olympic |
| 奥林匹克精神 | Ào lín pǐ kè jīng shén | Olympic spirit |
| 奥林匹克运动会 | Ào lín pǐ kè yùn dòng huì | Olympic Games; the Olympics |
奥林匹克运动会组
织委员会 | Ào lín pǐ kè yùn dòng huì zǔ zhī wěi yuán huì | Olympic organizing committee; abbr. to 奥组委 |
| 奥林匹克体育场 | Ào lín pǐ kè tǐ yù chǎng | Olympic Stadium |
| 奥尔巴尼 | Ào ěr bā ní | Albany, New York |
| 奥尔布赖特 | Ào ěr bù lài tè | (Madeleine) Albright (US Secretary of State) |
| 奥尔德尼岛 | Ào ěr dé ní dǎo | Alderney (Channel Islands) |
| 奥尔良 | Ào ěr liáng | Orléans |
| 奥特曼 | Ào tè màn | Ultraman, Japanese science fiction superhero |
| 奥特朗托 | Ào tè lǎng tuō | Otranto city on the southeast heel of Italy |
| 奥特朗托海峡 | Ào tè lǎng tuō hǎi xiá | strait of Otranto between the heel of Italy and Albania |
| 奥特莱斯 | ào tè lái sī | outlets (loanword); retail outlet (e.g. specializing in seconds of famous brands); factory outlet retail store |
| 奥卢 | Ào lú | Oulu (city in Finland) |
| 奥米伽 | ào mǐ gā | omega (Greek letter Ωω) |
| 奥米可戎 | ào mǐ kě róng | omicron (Greek letter Οο) |
| 奥组委 | Ào zǔ wěi | Olympic organizing committee; abbr. for 奥林匹克运动会组织委员会 |
| 奥维耶多 | Ào wéi yē duō | Oviedo (Asturian: Uviéu), capital of Asturias in northwest Spain |
| 奥兰多 | Ào lán duō | Orlando |
| 奥兰群岛 | Ào lán qún dǎo | Åland Islands, Finland |
| 奥西娜斯 | Ào xī nuó sī | Oceanus, Titan God of the seas before Poseidon |
| 奥赖恩 | Ào lài ēn | Orion (NASA spacecraft) |
| 奥赛罗 | Ào sài luó | Othello (play by Shakespeare) |
| 奥迪 | Ào dí | Audi |
| 奥迪修斯 | Ào dí xiū sī | Odysseus, hero of Homer's Odyssey |
| 奥迹 | ào jì | Holy mystery; Holy sacrament (of Orthodox church) |
| 奥运 | Ào yùn | abbr. for 奥林匹克运动会; Olympic Games; the Olympics |
| 奥运供货商 | Ào yùn gōng huò shāng | supply of Olympic merchandise |
| 奥运城市 | Ào yùn chéng shì | Olympic city |
| 奥运村 | Ào yùn cūn | Olympic Village |
| 奥运赛 | Ào yùn sài | Olympic competition |
| 奥里萨邦 | Ào lǐ sà bāng | Orissa, eastern Indian state bordering Bangladesh |
| 奥里里亚 | Ào lǐ lǐ yà | Aurelia, a hypothetical planet |
| 奥陶系 | Ào táo xì | Ordovician system (geology); see 奥陶纪 |
| 奥陶纪 | Ào táo jì | Ordovician (geological period 495-440m years ago) |
| 奥马哈 | Ào mǎ hā | Omaha |
| 奥马尔 | Ào mǎ ěr | Omar (Arabic name) |
| 奥黛莉 | Ào dài lì | Audrey; variant of 奥黛丽 |
| 奥黛丽 | Ào dài lì | Audrey |
安东尼与克莉奥佩
特拉 | Ān dōng ní yǔ Kè lì ào pèi tè lā | Anthony and Cleopatra, 1606 tragedy by William Shakespeare 莎士比亚 |
怪人奥尔・扬科维
奇 | guài rén Ào ěr · Yáng kē wéi qí | "Weird Al" Yankovic (1959-), US singer and writer of parody songs |
| 爱奥尼亚海 | Ài ào ní yà hǎi | Ionian sea between Italy and Greece |
| 爱奥华 | Ài ào huá | Iowa, US state |
| 爱奥华州 | Ài ào huá zhōu | Iowa, US state |
| 戴奥辛 | dài ào xīn | dioxin, carcinogenic heterocyclic hydrocarbon (esp. Taiwan usage) |
