Commonly Confused Words In English start on letter O
and How to Use Them

objective, subjective obligated, obliged obliged, obligated obtain, attain octopi, octopuses octopuses, octopi offence, offense offense, offence oftentimes, often times old-fashion, old-fashioned older, elder omelet, omelette on accident, by accident onboard, on board one’s self, oneself oneself, one’s self online, on-line onto, on to opaque, translucent opossum, possum oral, aural, verbal ordinal numbers, cardinal numbers ordinance, ordnance organisation, organization organization, organisation orientated, oriented oriented, orientated orthopaedic, orthopedic orthopedic, orthopaedic our, are out loud, aloud overnight, over night over time, overtime overtime, over time oppose, appose one, won ought, aught overdo, overdue obsolescent, obsolete official, officious ore, awe, or, oar of, off or try to, try osmosis, diffusion occupational therapy, physical therapy optometrist, ophthalmologist oligopoly, monopoly