Old Nubian
Old Ossetic
Old Persian (ca. 600-400 B.C.)
Old Provençal (to 1500)
Old Russian
Old Saxon
Old Spanish
Old Tamil
Old Tibetan
Old Turkish
Old Uighur
Old Welsh
Olekha
Olkol
Olo
Oloma
Olrat
Olu'bo
Olulumo-Ikom
Oluta Popoluca
Omagua
Omaha-Ponca
Omani Arabic
Ombamba
Ombo
Omejes
Ometepec Nahuatl
Omi
Ömie
Omok
Omotik
Omurano
Ona
Oneida
Ong
Önge
Onin
Onin Based Pidgin
Onjob
Ono
Onobasulu
Onondaga
Ontenu
Ontong Java
Oorlams
Opao
Opata
Opuuo
Orang Kanaq
Orang Seletar
ISO 639-3 Reference Names