An unspecified future time.
The definition of by-and-by is at an unspecified, future time and place.
An example of by-and-by used in a sentence is, "We'll go on that vacation by-and-by," which means we'll go on that vacation at some point in the future.
After a while; soon.
Some future time or occasion.
Alternative spelling of by and by.
After a short time.
After an indefinite period.
Sit down, have a rest, and by and by you'll be feeling better.