- obtuse
- organic laws
- on edge
- opaque
- outspoken
- off-time
- orange plant
- overblown
- obelus
- organ
- on the trot
- orator
- ochlophobia
- oil sardine
- one ideal
- old buffer
- ordinal
- opposite view
- overdress
- ocimum tenuiflorum
- overween
- overbid
- on the cards
- off pat
- out of phase
- oppression
- outrage
- on fire
- oceania
- overhang
- ostensible
- out of focus
- out of joint
- omelette
- o
- overload
- on the side of the grave
- osteoporosis
- oxfam
- on the wane
- overwhelmingly strong
- of one's own
- out of print
- open newel
- overture
- once
- offend
- outside work
- osi
- off the rails
- overdressed
- overhead projector
- oversight
- overwhelming
- office hours
- outfit
- outlive
- opposition
- oceanid
- ooze
- oppugn
- onanimpulse
- off spring's
- occupational
- out-take
- orientalize
- orbicularity
- occlude
- of late
- ovenware
- off the beat
- oncologist
- out on a limb
- on the line
- owner
- overrule
- off the cuff
- orang-outang, orangutan
- out of luck
- often
- overpower
- oviferous
- ox hydrogen
- out of the way
- octane
- own goal
- opalize
- osteoarthritis
- olive
- over the moon
- on the sidelines
- on the move
- overused
- obligatory
- obscenity
- observe
- obsessive
- obsolescent
- overflowing
- oil-crushers