| Firstname | Gender | Origin | Meaning of name | Form | Pronunciation |
|---|---|---|---|---|---|
| Octavia |  | Latin | Eighth | Octavius | (ahk TAY vee ah) |
| Odalys | | Germanic | Wealth | Odilia | (ODE ah lis) |
| Odessa | | Ukrainian | Place name | (o DEH sah) | |
| Odetta | | Germanic | Wealth | Odette | (oh DETT ah) |
| Oka | | Japanese | Cherry blossom | (OH kah) | |
| Okalani | | Hawaiian | From heaven | Itself | (OH kah la nee) |
| Oksana | | Greek | Welcoming | (ok SA na) | |
| Olene | | English | N/A | Ole | (oh LEEN) |
| Olga | | German | Holy | (OL gah) | |
| Olive | | English | Olive | Olivia | (AW liv) |
| Firstname | Gender | Origin | Meaning | Form | Pronunciation |
|---|---|---|---|---|---|
| Olivia | | English | Elf army | (o LIV ee ah) | |
| Olly | | English | Elf army | (AW lee) | |
| Olwen | | Welsh | White footprint | Itself | (OHL wen) |
| Olympia | | Greek | From Mount Olympus | Itself | (o LYEEM pee ah) |
| Olyvia | | English | Elf army | (oh liv ee uh) | |
| Onawa | | Wide awake | Itself | (oh NOW ah) | |
| Oneida | | The people of the stone | Itself | (o NIE dah) | |
| Onella | | Greek | Torch; bright light | Ilona | (O nel la) |
| Onia | | Hebrew | Ship | Oniya | (O nee yah) |
| Oona | | Latin | One | (OO na) |