- overstate
- oil-colours
- oracy
- omninescience
- outsourcing
- outstation
- oral presentation
- oceanography
- olio
- offside
- oxymoron
- onanism
- on the first instance
- over hastiness
- one-twelfth
- old top
- other-directed
- on the table
- on one mettle
- owe person a grudge
- on stilts
- on the record
- outboard
- ohm
- old bachelor
- out wardens
- open and above board
- on its merits
- ooze from
- oversleep
- on parole
- one who has not performed the ceremony of tonsure
- optical scanner
- object computer
- oast
- organic chemistry
- ordinary run of men
- overstaff
- onam
- obeisant
- own brand
- outrank
- overhead costs
- one with deformed limbs of without limbs
- outbound
- old saying
- oaten
- ostracise
- one who feeds
- oviparous
- oedipus
- otherness
- ogling
- on board
- one man
- orgies
- one that can excel
- overexposure
- ontology
- ochery
- oil squeezers
- one who dedicates
- och
- onliness
- oozing latex
- onto
- overexertion
- ominiscience
- owe to
- ostensibility
- on the safe side
- office bearer
- offense
- octavo
- oncology
- on one's high horse
- over toned
- orpiment
- odourless
- owner occupied
- of price
- on the stroke
- octopod
- out in one's reckoning
- overgrazing
- overdevelop
- outwear
- optometry
- oft-ignored
- oblong pond
- oersted
- ornithology
- old money
- objure
- on the stump
- oxygenation
- online
- obscura
- of the first water
- oxide