- one's declining years
- on the edge of one's seat
- of little value
- over-bearing
- over-peopled
- obeying
- once upon a time
- obliteration
- obesity corpulence
- occultism
- obsessive about
- on the bread line
- on the job
- on remand
- oxidize
- off-centre
- on the bottom
- opposer
- overruling
- other man
- overacted
- overfamiliar
- open to attack
- on the outs
- overcrowd
- on welfare
- overset
- odiousness
- osculation
- of substance
- over-critical
- overlooked
- old lag
- oblate
- on the stocks
- other than
- on the barrelhead
- on the same wavelength
- owners
- old stager
- on full alert
- out of humour
- overdose
- on one's last legs
- objecting
- on the doorstep
- ordinal number
- over-brim
- one-on-one
- ordinances
- offentimes
- on pins and needles
- opress
- one's cross to bear
- overplayed
- over-wrought
- ovenproof
- on the qui vive
- of importance
- obsecration
- or thereabouts
- outer limits
- on the stroke of something
- one's portion
- oojamaflip
- overhadow
- olde worlde
- on the wallaby track
- offcuts
- out-of-towner
- occurrences
- on the skew
- on the blink
- offprint
- old wives' tales
- of good report
- obligingly
- overwight
- owner-occupancy
- over and above that
- one's salad days
- off target
- of consequence
- out of sort
- over-dramatized
- outside of
- overemphasized
- overkill
- overload oneself
- of ample proportions
- overelaborate
- oojamafflip
- overpopulated
- on the streets
- outbalance
- outcold
- out of the ark
- owner-occupier
- on one's toe
- opium