Zigzag.
1. (Fortification.) One of the trenches leading toward the besieged works, and communicating between the several parallels. It turns to the right and to the left, but with a general curved course, in such a manner as not to be enfiladed by the guns of the fort. The approaches to Sebastopol, including the zigzags and parallels, embraced 70 miles of sunken trenches, and required no less than 60,000 fascines, 80,000 gabions, and 1,000,000 sandbags, to protect the men working in the trenches and at the different batteries. 2. A winding chute on the face of a dam to enable fish to ascend. A salmon-stair; fishway; fish-ladder.