What do you call a line with an arrow on each end?

Answer 1

Well, darling, that's what we call a "ray". It's like a line that decided to show off and grow a pointy edge on both sides. So, next time you see a line feeling fancy with arrows, just remember it's called a ray.

Answer 2

A line with a point at each end is known as a segment. A line with an arrow on each end, however, is known simply as a line.