- observation plane
- observation post
- observation station
- observational
- observatory
- observer
- observing
- obsess
- obsession
- obsessional
- obsidian
- obsolete
- obsoletism
- obstacle
- obstacle course
- obstacle race
- obstetric
- obstetrician
- obstetrics
- obstinacy
- obstinate
- obstinateness
- obstipation
- obstreperous
- obstruct
- obstruction
- obstruction guard
- obstructive
- obstruent
- obtain
- obtect
- obtest
- obtestation
- obtrude
- obtrusion
- obtrusive
- obtundent
- obturate
- obtuse
- obtuseness
- obverse
- obversion
- obvert
- obviate
- obviosity
- obvious
- obvolute
- oc-
- ocarina
- ocas
臉書專頁