- occupy oneself
- one's lot in life
- on an equal footing
- one-sidedness
- overwrite
- of immeasurable worth
- outflux
- officers of the law
- over-appreciative
- overlord
- owing someone a debt of gratitude
- off the subject
- oiled
- Ozalid
- of no moment
- off the latch
- of age
- on dry land
- opponents
- ordered
- on the bias
- old-maidish
- on the assumption that
- old codger
- orient oneself
- outpace
- off the top of one's head
- on one' own
- outst-anding
- on the attack
- otherworldly
- obsolescence
- occultation
- overtired
- overvalue
- only now
- old lady
- out of harmony
- outstanding payment
- objectives
- overdraw
- on the strength of
- out of shape
- on the map
- on record
- oddment
- on offer
- of yore
- one's cards
- orison
- on the lookout
- omitted
- outback
- over-wrouht
- of the order of
- overburden
- one's advancing years
- overnighter
- on the wagon
- out of touch with reality
- one of a kind
- only to be expected
- open to doubt
- opencast mine
- one after the other
- of the wall
- of the old school
- oral tradition
- occupier
- on the quiet
- one-party
- of no value
- of unsound mind
- outer edge
- one's career
- one-eighty
- out of line
- on the right lines
- of the utmost importance
- once and for all
- on everyone's lips
- on the never-never
- obscenities
- on the same wave-length
- oppugnant
- of value
- oriel
- offal
- opening statement
- ovid
- old saw
- occupied with
- open one's mouth
- orbshaped
- old-world
- ornithologist
- oceanic
- odysseys
- on a level with
- overplay