imaginary line

The lake was oval in shape, and an imaginary line drawn from shore to shore at its center would measure more than a mile.

Neither of them was prepared to rest content with a scientific frontier, an imaginary line.

That imaginary line which divides the earth into northern and southern hemispheres, and which is equally distant from each pole.

What a jumble, that by just crossing an imaginary line one finds people who can't understand a word one says!

The imaginary line, around which all the parts of a body revolve, when it has a spinning motion.