orthodontic treatment
— Noun
– English
～ dental treatment that corrects irregularities of the teeth or of the relation of the teeth to surrounding anatomy; treatment is usually by braces or mechanical aids; "orthodontic treatment of facial abnormalities"
oak tree
— Noun
– English
～ a deciduous tree of the genus Quercus; has acorns and lobed leaves; "great oaks grow from little acorns"
ordeal tree
— Noun
– English
～ evergreen shrub or tree of South Africa
orange tree
— Noun
– English
～ any citrus tree bearing oranges
orchid tree
— Noun
– English
～ small East Indian tree having orchid-like flowers and hard dark wood
orchard apple tree
— Noun
– English
～ native Eurasian tree widely cultivated in many varieties for its firm rounded edible fruits
olive-tree agaric
— Noun
– English
～ red luminescent mushroom of Europe
olive tree
— Noun
– English
～ a tree of the genus Olea cultivated for its fruit
order Tremellales
— Noun
– English
～ fungi varying from gelatinous to waxy or even horny in texture; most are saprophytic
on trial
— Adjective
– English
～ in the process of being tested or tried
oblique triangle
— Noun
– English
～ a triangle that contains no right angle
obtuse-angled triangle
— Noun
– English
～ a triangle that contains an obtuse interior angle
obtuse triangle
— Noun
– English
～ a triangle that contains an obtuse interior angle
order Trichoptera
— Noun
– English
～ an order of insects consisting of caddis flies
one-trillionth
— Noun
– English
～ one part in a trillion equal parts
ocean trip
— Noun
– English
～ an act of traveling by water
os triquetrum
— Noun
– English
～ a wrist bone that articulates with the pisiform and hamate and lunate bones