A traditional cloth weave using a pattern of oblique lines set in alternate rows. This gives a distinct "V' pattern to the material. Othen found in better men's suits (not the $99 Tip Top special).

This term is also applied to similar patterns when found in nature (crystal growth) or the works of man (drainage systems, skier tracks as they trudge uphill).

Compare houndstooth check.

rootbeer277 points out that herring bone is also a gear pattern (explained there).