1. superlative form of hilly; having the most hills or the greatest number of hills
Usage: superlative degree

Examples

• The hilliest part of the state is in the western region.
• This hiking trail is the hilliest one in the park system.
• Of all the neighborhoods, that one is the hilliest and hardest to bike through.
• The hilliest terrain made the race more challenging for the runners.
• We chose the hilliest route to get a better workout.