- ostrich policy
- otalgia
- owlish
- otherwise
- onerousness
- one who intimates
- out of sorts
- out of spirits
- out of temper
- one who ignores household duties as laid down by the scriptyres
- out of the straight
- outlay
- one who gives joy
- one who erects
- outpoint
- outrageous
- outside
- overwrought
- one who collects customs-tax
- on behalf of someone, on someone's behalf
- overbalance
- overcome
- overdue
- one who acts
- overturn
- overweight
- oxygen mask
- on the rove
- on the nail
- on no account
- on cost
- olivaceous
- olibanum
- olfaction
- olent
- old-fashioned
- old man
- officiator
- officiate
- on average
- overwhelm
- on balance
- on the beam
- offended
- off-peak
- off the wall
- overthrow
- oddity
- odd jobs
- overcrowded
- oculist
- octuple
- overconfident
- on cloud nine
- oceanus
- ocean
- occurence
- of course
- occident
- oblique
- obligation
- objectivity
- objectively
- objectionable
- object
- overawed
- overbearing
- on sight
- over worn
- optical centre
- out of doors
- one track
- on the score of absurdity
- overindulgence
- onwardness
- opposite sides
- overbold
- over-talkativeness
- operculum
- on the face of it
- one with another
- obligingness
- optician
- on approval
- ogrism
- over sleepy
- overfishing
- one who indulges in insolence
- oevre
- one who submits
- optical character recognition
- over careful
- ordinate
- one who chants sama veda
- of even date
- order out
- out in the cold
- office-seeker
- one who has a share
- outshine