This is the 5463rd most frequent Spanish word.
ondulado
"Wavy."
The word "ondulado" here is used as an adjective to describe the hair, indicating its texture, which is wavy.
Ella tiene el cabello ondulado.
She has wavy hair.
In this context, "ondulado" describes the terrain as having a wavy or uneven surface, used metaphorically to describe the ups and downs.
El camino hacia la cima pasa por un terreno ondulado.
The path to the summit goes through a rolling terrain.
Here, "ondulado" is used to describe the design pattern of the paper, indicating it has a wave-like appearance.