(mathematics) An instance, or the process, of cross-multiplying.

To set the product of the extremes of a proportion equal to the product of its means.

A burning cross made of wood, historically used to rally troops.

plural of cross-staff

Alternative form of cross-purpose

(geometry) A special number associated with an ordered quadruple of collinear points, particularly points on a projective line, and preserved by the fractional linear transformations.

Able to use, connect, interact, and function universally with various systems.

(transitive, intransitive) To sell (additional products) to existing customers.

The act of making such a sale.

Alternative form of crosskick