- oximoron
- one who submits
- owls
- oxidizable
- optical character recognition
- one who pities
- over careful
- of one and one only
- orthogonal
- overcompensate
- over plus
- overt
- oil-mill
- one who has a share
- outness
- orissa
- overgrow
- opined
- one who eats
- one who is inactive
- one who is not done his duties
- one who reads
- one who sleeps at sunrise
- one who throws
- onewho repeats what another says
- onion-skin
- off the shelf
- onlooker
- only
- onomatoepic
- onomatopoeic
- onus
- onymous
- oogenesis
- oophorectomy
- one short of
- openly
- operational
- ophthalmic
- ophthalmologist
- opine
- opinionative
- overvaluation
- opium-den
- optician
- ordinary fly
- ordinary man
- ordnance
- orectic
- oregano
- organiser
- oriental
- original
- ostentation
- osteomalacia
- ostracize
- ostrich policy
- otalgia
- over praising
- otherwise
- on approval
- one rate
- out of sorts
- out of spirits
- out of temper
- ogrism
- out of the straight
- overdo
- outlay
- overemphasize
- opera
- orange
- one who scratches
- outpoint
- outrageous
- outside
- overheads
- overindulge
- outer skin
- overexpose
- out-herod
- out of heart
- overpowering
- one-fourth
- overreact
- oversea, overseas
- out of time
- overbear
- on account of
- oevre
- out of the woods
- odeum
- outgoer
- ordinate
- old sores
- obscene words
- one who chants sama veda
- of even date
- open old wounds
- omni