| Omkareshwari | - | Hindu Name | Omkari | - | Hindu Name |
| Omnia | - | Arabic Name | Omolara | - | Cameroon Name |
| Omorose | - | Egyptian Name | Omvati | - | Indian Name |
| Omvati | - | Hindu Name | Ona | - | African Name |
| Onaedo | - | American Name | Onaona | - | Polynesian Name |
| Onara | - | Assyrian Name | Onawa | - | American Name |
| Onchuma | - | Thai Name | Ondina | - | Portuguese Name |
| Onelia | - | Philippines Name | Onella | - | Hindu Name |
| Oneng | - | Indonesian Name | Oni | - | Egyptian Name |
| Onida | - | American Name | Onika | - | Andalusi Name |
| Onira | - | Cyprien Name | Onna | - | Irish Name |
| Onnaree | - | Thai Name | Onnicha | - | Thai Name |
| Ono | - | Biblical Name | Onome | - | Cameroon Name |
| Onora | - | Gaelic Name | Onorina | - | Philippines Name |
| Onsa | - | Basque Name | Onufriya | - | Ukrainian Name |
| Onuma | - | Thai Name | Onyx | - | Greek Name |
| Onyx | - | United States Name | Onyxia | - | American Name |
| Ookika | - | Eskimo Name | Oola | - | Aborigin Name |
| Oona | - | Finnish Name | Oorja | - | Hindu Name |
| Oormila, Urmila | - | Hindu Name | Opal | - | English Name |
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