1.a mark or stroke long in proportion to its breadth, made with a pen, pencil, tool, etc., on a surface:
a line down the middle of the page.
2.Mathematics. a continuous extent of length, straight or curved, without breadth or thickness; the trace of a moving point.
3.something arranged along a line, especially a straight line; a row or series:
a line of trees.
4.a number of persons standing one behind the other and waiting their turns at or for something; queue.