In general, an imaginary line is any sort of line that has only an abstract definition, and does not exist in fact.
As a geographical concept, an imaginary line may serve as an arbitrary division (such as a border). It may also be a standardized mark that serves as a measurement or point of reference (such as a circle of latitude or the Prime Meridian).
Famous quotes containing the words imaginary and/or line:
“I am giddy; expectation whirls me round.
Th’ imaginary relish is so sweet
That it enchants my sense.”
—William Shakespeare (1564–1616)
“It is a great many years since at the outset of my career I had to think seriously what life had to offer that was worth having. I came to the conclusion that the chief good for me was freedom to learn, think, and say what I pleased, when I pleased. I have acted on that conviction... and though strongly, and perhaps wisely, warned that I should probably come to grief, I am entirely satisfied with the results of the line of action I have adopted.”
—Thomas Henry Huxley (1825–95)