Traversing involves running a hand plane across the width of a board rather than parallel to its grain. This technique is used during the initial flattening of rough or cupped lumber, as cutting across the fibers removes material quickly without causing deep tear-out. Once the board is flat, the woodworker switches to planing with the grain for a smooth final surface.
Heard on the job
The slab is badly cupped, so you'll need to traverse it with the scrub plane first.