The x-coordinate of a point is called Abscissa. It is the perpendicular distance measured from the y-axis along the x-axis.
The y-coordinate of a point is called Ordinate. It is the perpendicular distance measured from the x-axis along the y-axis.
For the point (1,2), its abscissa is 1 and its ordinate is 2
For the point (2,1), its abscissa is 2 and its ordinate is 1.