a line is an endless collection of points that follow a straight path. there is no start and finish and there are no curves.
"imaginary" does not describe a line by definition because lines are definite points, not imaginary ones. "endless" does describe a line because, as stated, they have no start or finish. "curved" does not describe a line, because lines follow a straight path. "has no width" describes a line accurately because lines are one dimensional; when we imagine a line, we visualize it by drawing one with a certain width, but in geometry, lines do not have any width. it's just a representation. a line additionally does not "have two endpoints"--that would be a line segment, with a starting point and a finishing point. lines go on forever in both directions, so you wouldn't be able to find endpoints for it.
