1. To move along in a back and forth or right to left procedure: The trail up the mountain was zigzagging all the way to the top.
2. Etymology: from French which came from German Zickzack, "the alternation of directions" which may have applied to fortifications.

To progress forward by moving in alternating and abrupt directions: Tom had to zigzag across the parking lot in order to avoid all the puddles of water which collected after the downpour the night before.