Pob tudalen â rhagddodiad
- Obadeia
- Objective 1
- Objekt
- Occitan
- Oceania
- Ocsitaneg
- October
- Odlau:Cymraeg:-a
- Odlau:Cymraeg:-ab
- Odlau:Cymraeg:-abl
- Odlau:Cymraeg:-abr
- Odlau:Cymraeg:-ac
- Odlau:Cymraeg:-ach
- Odlau:Cymraeg:-acht
- Odlau:Cymraeg:-acl
- Odlau:Cymraeg:-acr
- Odlau:Cymraeg:-act
- Odlau:Cymraeg:-ad
- Odlau:Cymraeg:-add
- Odlau:Cymraeg:-adl
- Odlau:Cymraeg:-adn
- Odlau:Cymraeg:-adr
- Odlau:Cymraeg:-ae
- Odlau:Cymraeg:-aech
- Odlau:Cymraeg:-aed
- Odlau:Cymraeg:-aedd
- Odlau:Cymraeg:-aeg
- Odlau:Cymraeg:-ael
- Odlau:Cymraeg:-awns
- Odlau:Cymraeg:-awr
- Odlau:Cymraeg:-eg
- Odlau:Cymraeg:-esb
- Odlau:Cymraeg:-oyw
- Ogos
- Old Cornish
- Old English
- Old French
- Old Testament
- Orange
- Organismus
- Oslo
- Ostrowiec Świętokrzyski
- Ottoman Empire
- Oxford
- Oxonian