- operating costs
- overwrite
- on vacation
- obstacles
- ordered
- overfull
- on dry land
- outreach
- owing to the fact that
- of one voice
- on your way
- one-sidedness
- Ozalid
- off the subject
- others
- obtrusion
- off drugs
- overlord
- one's marching orders
- opponents
- occultation
- objectives
- of unsound mind
- on record
- of the utmost importance
- outer edge
- overdraw
- obscenities
- on one' own
- on the attack
- old codger
- oral tradition
- occupied with
- overburden
- orison
- outst-anding
- outback
- odysseys
- only to be expected
- old saw
- otherworldly
- of the order of
- old lady
- overvalue
- out of harmony
- open to doubt
- obsolescence
- one's cards
- opencast mine
- outpace
- one after the other
- on the bias
- offal
- of yore
- oceanic
- of value
- on the wagon
- of the old school
- on a level with
- occupier
- on the lookout
- one-party
- orient oneself
- off the top of one's head
- on the right lines
- on everyone's lips
- overnighter
- on the never-never
- on the same wave-length
- omitted
- old-world
- overtired
- only now
- one-eighty
- open one's mouth
- ovid
- oriel
- outstanding payment
- on the assumption that
- old-maidish
- on the strength of
- of the wall
- one's career
- on the quiet
- ornithologist
- oddment
- oppugnant
- out of line
- one of a kind
- on offer
- once and for all
- of no value
- over-wrouht
- opening statement
- orbshaped
- overplay
- out of touch with reality
- one's advancing years
- on the map
- out of shape