David Folds a sheet of paper. The dotted lines as shown in the figure are the creases formed, which are named as l, m and n.

 

What do you call the line n with resect to the lines l and m?

From the figure, we can say:

n bisects l and m at distinct points, and l and m are parallel to each other and the angle created by line n with line n is equal to the angle created by line n and m.

Thus, n is called a Transversal line.