obtu - orna
- obtuse
- obtuse leaf apex
- obtuse-angled box tenon
- obtusifolious
- occasional chair
- occasional furniture
- occasional table
- Occella verrucoga
- occluded knot
- occluded soap
- occlusion
- occupation of the seabed
- occurence on board a vessel
- ocean crust
- ocean current
- ocean data acquisition systems
- ocean deeps
- ocean engineering
- ocean mining
- ocean pout
