- overload
- otto of roses
- obsequiousness
- out of place
- overpower
- old money
- obsolete
- overrule
- obstetric
- ornithology
- obstruct
- oversight
- obtain
- oology
- obtainable
- out of practice
- obtuse angle
- of wide fame
- obviousness
- overture
- occasion
- o baptize
- out of service
- overused
- occupied
- object lesson
- odd man out
- overwhelming
- odious
- opportunist
- oenophile
- out of spirits
- on the streets homeless
- owner
- on time punctually
- overarm
- out of temper
- octopod
- outcry
- obsession
- oligarchy
- one who punishes
- of one's own accord
- off pat
- of one's own free will
- one shot
- on the gui vive
- outside verandha
- one-way
- oxygen tent
- of
- overnight
- open persons eye
- on terms of
- oil-colours
- oracy
- omninescience
- ocherous
- outsourcing
- outstation
- oral presentation
- oblige someone with
- oceanography
- olio
- offside
- oxymoron
- old testament
- onanism
- on the first instance
- over hastiness
- one-twelfth
- old top
- offal pit
- other-directed
- on the table
- on the ropes
- on one mettle
- owe person a grudge
- on stilts
- olericulture
- on the record
- outboard
- orientated
- ohm
- old bachelor
- out wardens
- open and above board
- on its merits
- ooze from
- oversleep
- occlussion
- on parole
- one who has not performed the ceremony of tonsure
- optical scanner
- out bar
- object computer
- oast
- organic chemistry
- one who does the milching
- opera-house