short for Australia, known in Chinese as 澳大利亚 ào​dà​lì​yà

short for Macao, known in Chinese as 澳门 ào​mén

deep bay; cove; harbor; a sea inlet that can shelter boats (often used in place names)

the Chinese surname Ao

(literary) the curve of a river bank

short for Oceania, known in Chinese as 大洋洲 dà​yáng​zhōu

(literary) deep; profound