(n) open-necked shirt (wasei: open shirt)
(n) oil shale
(n) oil crisis, es. 1973 OPEC oil crisis (wasei: oil shock)
(n) (uk) traveller's tree (Ravenala madagascariensis)
traveller's palm
(n) (uk) Oshima cherry (Prunus speciosam, P. lannesiana var. speciosa)
(n) (uk) ooba (big leaves) plantation lily
Hosta sieboldiana
(n) oxygenase (ger: Oxygenase)
(n) oxidant cloud
(n) oscilloscope
(n) oscillometer
(n) ostracism
(n) (1) tadpole
(2) ladle
(3) musical note
(n) (comp) offshore development
(n) offshore market
(n) off shoulder
(n) obsession
(n) (comp) Option key
(n) option contract
(n) option trading
option dealing
option transaction
(n) operation
(P)
(n) ovation
(n) card system
(n) carnation
(P)
(n) cashew nuts
(n) kasugamycin
(n) (uk) Japanese anchovy (Engraulis japonica)
(n) cutter shirt (long-sleeved sports shirt)
(n) (uk) Portuguese man-of-war (Physalia physalis)
(n) Protura (order of wingless insects)
(n) Protura (order of wingless insects)