outer planet
— Noun
– English
～ (astronomy) a major planet whose orbit is outside the asteroid belt (Jupiter, Saturn, Uranus, Neptune, Pluto)
ovulation method of family planning
— Noun
– English
～ natural family planning in which the fertile period is inferred from changes in the character and quantity of cervical mucus; ovulation is marked by an increase in mucus that becomes sticky and then clearer and slippery
onion plant
— Noun
– English
～ bulbous plant having hollow leaves cultivated worldwide for its rounded edible bulb
orchidaceous plant
— Noun
– English
～ any of numerous plants of the orchid family usually having flowers of unusual shapes and beautiful colors
okra plant
— Noun
– English
～ tall coarse annual of Old World tropics widely cultivated in southern United States and West Indies for its long mucilaginous green pods used as basis for soups and stews; sometimes placed in genus Hibiscus
obedience plant
— Noun
– English
～ white-flowered West Indian plant whose root yields arrowroot starch
obedient plant
— Noun
– English
～ North American plant having a spike of two-lipped pink or white flowers
oyster plant
— Noun
– English
～ long white salsify