=Octavus=, _n._ L. _octavus_, eighth; given in this book as a name to
a suppositional plant.
=Oil=, _n._ From a Greek word meaning “olive oil.” An inflammable,
greasy liquid extracted from certain vegetables, as olives, cotton
seeds, nuts, etc.
=Olive oil=, _n._ The oil expressed from the fruit of the olive tree.
=Orient=, _n._ L. _oriens_, rising, as the sun; the East, the part of
the horizon where the sun rises; Eastern countries, particularly
Turkey, Persia, Egypt, India, China, etc.
=Ovary cells=, _n._ The cells which build up the ovary.
=Ovule=, _n._ L. _ovum_, an egg; a little egg. Applied to the
rudimentary seeds of plants, which, upon fertilization and growth,
become true seeds.
=Ovule cells=, _n._ The cells of which the ovule is formed.
=Oxalis=, _n._ From a Greek word meaning “acid”; a well-known plant,
one form of which is called “wood sorrel.” It is called oxalis
because of its acid juice.
=Oxygen=, _n._ One of the gases that compose the air and which is
essential to life. It is also found in composition in the tissues of
plants and animals.