Corrugation

Corrugation is a pattern of regular folds, ridges, or waves in a material, like the ripples in corrugated cardboard or metal roofing.

It comes from Latin “corrugare,” meaning “to wrinkle” or “to bend into folds,” from “com-” (together) and “rugare” (to wrinkle). So it literally refers to making something wrinkly or ridged.