- obstructive
- oddments
- offhand
- ogress
- omnipotence
- opposite
- opulent
- out-and-out
- overemphasize
- owing to
- own
- off the record
- on the spur of
- orthogonal
- ornithophily
- organelle
- obstetrics
- opera
- order from the top
- overlordship
- ocean in
- office-seeker
- oil-monger
- one who chants sama veda
- old sores
- open glass
- overjoy
- out of the woods
- ouch
- oneration
- old story
- over-talkativeness
- opposite sides
- ozone
- one track
- ocelot
- out of job
- optical centre
- oafish
- oarsman
- obeisance
- obey
- obscurity
- observation
- observing
- obtrusive
- obvious
- odontology
- oedema
- off the wall
- off-peak
- offended
- officiate
- officiator
- old man
- old-fashioned
- olent
- olfaction
- olibanum
- olivaceous
- on cost
- on no account
- on the nail
- on the rove
- one who acts
- one who collects customs-tax
- one who erects
- one who gives joy
- one who ignores household duties as laid down by the scriptyres
- one who intimates
- onerousness
- one who reprimands
- open-minded
- open-mouthed
- opportunity
- opposite shore
- oppressive
- optimism
- ore
- orexis
- organ of sense
- organized
- origami
- origin
- ossify
- ostenation
- ostentatious
- ostrich
- otorhinolaryngology
- ours
- out of the ordinary
- out of the question
- out roar
- out-of-tune sound
- outbid
- outbreak
- outburst
- outlier
- outlined
- outlying