In geography, a quadripoint is a point on the Earth that touches four distinct regions. Such points are often called "four corners", from the corners of the four regions meeting thereOne could argue that, if one region lies on one side of a straight line border, and the other three are on the opposite side of this line, there are only three "corners" plus a straight line. However in geometry the straight line in this context would be considered to form a straight angle measuring 180°.