English abbreviations from obu to oca
- OBU (Kobuk Airport)
- OBX (Outer Banks (North Carolina))
- OBY (Ittoqqortoormiit Heliport)
- oc (Occitan language (ISO 639-1 code))
- O.C. (Ordo C(h)aritatis (Fathers of the Order of Charity))
- OC's (Optical centres)
- OC/T (Observer Controller/ Trainer)
- OCA (Observatoire de la Côte d'Azur||Offensive Counter-Air)
