An absolute coordinate refers to a Cartesian System that uses X, Y, and sometimes a Z-axis to establish a point from a common origin. For example, in the picture to the right, the origin point is 0,0 and the absolute coordinate from that point is 8,7 making it 8 along the X-axis and 7 along the Y-axis.
As an example, in a CAD program you could draw a line using absolute coordinates. To do this start by entering the X,Y value of your origin point. To start a line at one to the right, and four up, as shown in the picture to the right, type 1,4. The line could then be drawn four to the right by using the absolute coordinate of 5,4.