Homography

Part of speech: noun (n.)

1. That method of spelling in which every sound is represented by a single character, which indicates that sound and no other.

2. A relation between two figures, such that to any point of the one corresponds one and but one point in the other, and vise versa. Thus, a tangent line rolling on a circle cuts two fixed tangents of the circle in two sets of points that are homographic.