- out of the woods
- oevre
- overbear
- out of time
- one-fourth
- one who indulges in insolence
- overexpose
- overfishing
- outer skin
- opthalmologist
- orange
- one rate
- originating
- on approval
- optician
- odd man
- overvaluation
- one short of
- off the shelf
- opined
- orissa
- outness
- oftenness
- obligingness
- oneration
- orchidaceous
- one who deserves to be pitied
- operculum
- oil-seed
- onomasticon
- oilier
- old story
- over-talkativeness
- on a shoe string
- oliver
- old as adam
- oneiric
- owning a mistake
- oily grain
- oxidator
- overland
- oyster
- overreaction
- one-tenth
- opposite sides
- owing one a grudge
- open one's eyes
- ozone
- outgrow
- on the score of absurdity
- outbrave
- one track
- onomatopoeia
- oniomania
- osseous
- optical centre
- orchid
- oestrogen
- on patrol
- on sight
- overawed
- option
- object
- objectionable
- objectively
- objectivity
- obligation
- oblique
- occident
- occurence
- ocean
- oceanus
- octuple
- oculist
- odd jobs
- oddity
- off and on
- officinal
- officious
- oh save!
- oil nuts
- ology
- ominous
- omnipresence
- on a par witih
- on someone's tail following
- on tap
- on the in crease
- on tow
- once more and again
- one in a thousand
- onerary
- ones own affair
- one's own flesh and blood
- open-minded
- open-mouthed
- optophone
- oral
- orate
- oration