A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
O
| Language name | Native name | Code |
|---|---|---|
| Occitan | Occitan | OCI |
| Official Aramaic; Imperial Aramaic | ܐܪܡܝܐ | ARC |
| Ojibwa | ᐊᓂᔑᓇᐯᒧᐏᐣ | OJI |
| Oriya | ଓଡ଼ିଆ | ORI |
| Oromo | Afaan Oromoo | ORM |
| Osage | - | OSA |
| Ossetian; Ossetic | Ирон Ӕвзаг | OSS |
| Otomian languages | - | OTO |