What does Crosshatch mean?

A unique type of denim that shows a square grid-like pattern in the weave. It is created by mixing uneven yarns in both the weft and warp directions.

Heddels explains Crosshatch 

Crosshatch denim is denim that has been woven using uneven, or slub, yarn for both the warp and weft threads. It is a more rare type of denim and develops a unique crisscrossed pattern as it fades.

Additional Resources

Up-close look at crosshatch denim: