A "thinking man's" figure. Dancers who are told to Crossrun will walk forward in a small arc to the "mirror image" of the spot they would go to if told simply to Run. Inactives, as in Run, will slide into the adjacent spot vacated by the Crossrunner. From a wave, Centers crossrun would require the centers to move to the opposite end of the wave from the end they'd move to if the call had been Centers Run. From a line of four, ends crossrun would require those ends to move to the far center rather than the near center (ans pass right shoulders with the other Crossrunner on the way).
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.