English–Japanese dictionary: O
- oak
- oasis
- ob-gyn
- obedient
- obesity
- object
- object marker
- objection
- objective
- objectivity
- observation
- observe
- obsession
- obstacle
- obstruct
- obvious
- occasionally
- occupation
- occurrence
- ocean
- ocean current
- octopus
- odd number
- oden
- of course
- off
- offensive
- offer
- offering
- offhand
- office
- office worker
- officer
- official
- official business
- official duties
- official name
- official residence
- official stance
- official website
- often
- ogre
- oh
- oil
- oil painting
- okay
- okinawa
- okra
- old
- old acquaintance
- old age
- old person
- older
- older brother
- older person
- older sister
- olympics
- omelet
- omen
- ominous
- on
- on and on
- on duty
- on earth
- on foot
- on one's back
- on one's own
- on purpose
- on the other hand
- on the plane
- on the street
- on the water
- on the way
- on top of that
- once
- one
- one after another
- one bowl of
- one breath
- one by one
- one color
- one defeat
- one hand
- one hour
- one hundred
- one hundred million
- one layer
- one letter
- one month
- one night
- one-night stay
- one o'clock
- one of the two
- one of two
- one or two
- one part
- one person
- one room
- one's all
- one's company
- one's heart's content
- one's own convenience
- one's own work
- one's surroundings
- one's turn
- one sheet
- one side
- one-sided
- one size larger
- one step
- one thing or another
- one thousand
- one vehicle
- one vote
- one-way
- one year
- one yen
- oneself
- onion
- online
- online shopping
- only
- only child
- ono
- onset
- onset of an illness
- oops
- open
- open field
- open recruitment
- open sea
- opening
- opening a business
- opening a store
- opening and closing
- opening for business
- opening match
- opening to traffic
- openly
- opera
- operation
- ophthalmology
- opinion
- opportunity
- opposite
- opposite bank
- opposite effect
- opposite sex
- opposite side
- opposition
- opposition party
- oppression
- optimism
- option
- optional
- or
- or more
- oral
- oral statement
- orange
- orbit
- orchestra
- ordeal
- order
- order received
- orders
- ordinance
- ordinary
- ordinary people
- organ
- organic
- organism
- organization
- organize
- organizer
- orientation
- origin
- original
- original text
- original work
- originally
- originator
- orphan
- orthodox
- orthopedic surgery
- osaka
- osaka-kobe area
- other
- other day
- other party
- other people
- other side
- other way
- others
- our company
- out of print
- out of service
- outdoors
- outfield
- outfit
- outing
- outlet
- outline
- outlook
- output
- outrageous
- outside
- outside the region
- outstanding
- oval
- ovary
- oven
- over there
- overall
- overcoat
- overcoming
- overcrowding
- overfamiliar
- overflow
- overhead
- overlap
- overnight stay
- overseas
- overseas posting
- overseas travel
- overserious
- oversleeping
- overtime
- overturn
- overview
- overwhelm
- overwhelming
- overwork
- owl
- owner
- ownership
- ox
- oxidation
- oxygen
- oyster