O字母开头的单词或词组(第14页)：
- opulent
- oration
- oratorio
- oracle
- oratory
- orchard
- orchestra
- ordain
- ordeal
- ordinance
- ordnance
- ore
- originality
- organism
- orient
- original
- ornate
- ornithology
- orthodontics
- orthodox
- oscillate
- osmosis
- osseous
- ossify
- ostensible
- ostentation
- ostracism
- ostracize
- ostrich
- other-directed
- otter
- oust
- outgoing
- outgrowth
- outline
- outlet
- outlandish
- outmaneuver
- outmoded
- outset
- outrage
- outshine
- outskirts
- outspoken