1. the quality or state of being hilly; the degree to which a landscape is characterized by hills

Examples

• The hilliness of the terrain made the hiking trail challenging.
• The region's hilliness provides beautiful scenic views.
• Cyclists often complain about the hilliness of this route.
• The hilliness of the landscape varies greatly from north to south.
• Despite the hilliness, the area is popular with outdoor enthusiasts.
• The map clearly shows the hilliness of the mountainous region.