- one hundred percent
- orbiting
- operating costs
- overwrite
- outreach
- on bended knee
- one's lot in life
- old warhorse
- Ozalid
- old boy
- oiled
- others
- onrush
- of little importance
- old fashioned
- other woman
- on the jungle telegraph
- on the right track
- of one voice
- on top of that
- occupier
- open to doubt
- only now
- offal
- overdraw
- outer edge
- of yore
- on the attack
- oriel
- on everyone's lips
- old saw
- of the utmost importance
- outst-anding
- omitted
- of unsound mind
- old-world
- of the order of
- on a level with
- oral tradition
- on the wagon
- only to be expected
- of value
- one's cards
- on one' own
- opencast mine
- overnighter
- of the old school
- ovid
- open one's mouth
- out of harmony
- on the lookout
- orison
- on record
- one-eighty
- odysseys
- overburden
- outback
- on the right lines
- one-party
- obscenities
- on the same wave-length
- oceanic
- on the never-never
- occupied with
- one after the other
- on the quiet
- over-wrouht
- off the top of one's head
- out of touch with reality
- once and for all
- old codger
- one of a kind
- overtired
- orbshaped
- out of line
- obsolescence
- on the strength of
- old-maidish
- overvalue
- overplay
- objectives
- ornithologist
- on the assumption that
- one's career
- out of shape
- one's advancing years
- outpace
- oddment
- of the wall
- oppugnant
- on offer
- on the bias
- orient oneself
- on the map
- old lady
- occultation
- outstanding payment
- otherworldly
- opening statement
- of no value