cross ratio

noun

, Geometry.

1. a ratio relating four points in the real or complex plane.

Other Words From

• cross-rati·o adjective

Word History and Origins

Origin of cross ratio¹

First recorded in 1880–85

Example Sentences

Before we draw conclusions from this result, we must investigate the meaning of a cross-ratio somewhat more fully.

From Project Gutenberg

If we take the points in a different order, the value of the cross-ratio will change.

From Project Gutenberg

It is convenient to let the point at infinity occupy the last place in the symbolic expression for the cross-ratio.

From Project Gutenberg

The cross-ratio of any four points in one equals that of the corresponding points in the other.

From Project Gutenberg

In other words, four lines in a flat pencil are cut by every other line in four points whose cross-ratio is constant.

From Project Gutenberg