Vocabulary consisting only from characters you are able to read
露天風呂
rotenburo
open air bath/rotemburomix
原っぱ
harappa
open field/empty lot/plain/(P)leda1
直火
jikabi
open fire, direct heatmix
開放
kaihou
open, throw open, liberalization, liberalisationsuru
開店
kaiten
opening (of a shop)suru
開閉
kaihei
opening and shuttingsuru
開会
kaikai
opening of a meetingsuru
開通
kaitsuu
opening, open, taking effect, becoming activesuru
稼動
kadou
operation (of machine)/actual workmix
大作戦
daisakusen
operation, planmix
眼科
ganka
ophthalmologymix
視点
shiten
opinion, point of view, visual pointmix
契機
keiki
opportunity, chancemix
野党
yatou
opposition party, political opposition, oppositionseiji
反対
hantai
opposition, resistance, antagonism, hostility, contrast, objection, dissension, reverse, opposite, vice versajlpt3, jlpt4, leda1, suru
反抗
hankou
opposition/resistance/insubordination/defiance/hostility/rebellion/(P)leda1, suru
楽観的
rakkanteki
optimistic, hopefulemo
最適
saiteki
optimum, the most suitablemix
口承文学
koushoubungaku
oral literature, oral traditionmix
順序
junjo
order, sequence, proceduremix
体制
taisei
order, system, structure, set-up, organization, organisationmix
常微分方程式
joubibunhouteishiki
ordinary differential equationmath
何の変哲もない
nannohentetsumonai
ordinary, plain, commonplaceadj
鉱石
kouseki
ore, mineral, crystalmix
器官
kikan
organ (of body), instrumentmix
団体
dantai
organization, organisation, associationjlpt3
構成
kousei
organization, organisation, configuration, compositionsuru
主催
shusai
organization, organisation, sponsorshipsuru
体系化
taikeika
organization, organisation, systematization, systematisationsuru
原点
genten
origin (coordinates), starting pointmix
起源
kigen
origin, beginning, risemix
由来
yurai
origin, source, history, derivation, reason, destinyall
原意
gen'i
original meaningmix
原状
genjou
original statemix
目新しい
meatarashii
original, novel, newadj
独自
dokuji
original, peculiar, characteristic, proprietarymix
元来
ganrai
originally, primarily, essentially, logically, naturallymix
元祖
ganso
originator, founder, pioneer, inventormix
装飾品
soushokuhin
ornament, decorationmix
孤児
koji
orphan; orphanmix
大阪府
oosakafu
Osaka (metropolitan area)namae
振動
shindou
oscillation, vibrationsuru
他
hoka
other (esp. places and things)/the restadj, leda1
外
hoka
other place, the restjlpt5
他府県
tafuken
other prefecturesmix
余人
yojin
others, other people; others, other peoplemix
乙姫
otohime
Otohime, daughter of Ryuujinkami
故障中
koshouchuu
out-of-ordermix
場違い
bachigai
out-of-place, inappropriate, sticking out like a sore thumbmix
州外
shuugai
out-of-statemix
宿
yado
outcasts (those from Kamakura period to the Edo period, common around the Kyoto region); inn, lodgingmix
屋外
okugai
outdoors, alfrescomix
外出
gaishutsu; sotode
outing, trip, going out; (n,vs) outing, trip, going outsuru
域外
ikigai
outside the areamix
向こう
mukou
over there, opposite direction, across the wayjlpt3, jlpt5
優勝
yuushou
overall victory, championshipsuru
飲み過ぎ
nomisugi
overdrinking, excessive drinkingmix
重なり
kasanari
overlapping, piling, stackingmix
馬鹿丁寧
bakateinei
overly polite, excessively polite, polite to a faultmix
持ち主
mochinushi
owner, proprietormix