The initial idioms of the letter O

one and only	one and the same
one another	one at a time
one bad apple spoils the (whole) barrel	one bad apple spoils the (whole) bunch
one bad apple spoils the (whole) bushel	one brick short of a (full) load
one brick shy of a load	one by one
One cannot be in two places at once	One cannot love and be wise
one card shy of a (full) deck	one day
one day chicken and the next day feathers	devil of a
one eye on	false move
one fell swoop	one fell swoop, in
one final word	one flesh
one foot in the grave, have	one for the books
one for the Gipper	one for the road
one small step for man, one giant leap for mankind	One good turn deserves another
one half of the world does not know how the other	One hand for oneself and one for the ship