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