Hill/hɪl/ Definition 1 of 6Pro Tip 1/3Size perception Hills are smaller than mountains, making them the lesser challenge in metaphors. Starting this business is a hill, not a mountain. Pro Tip 2/3Physical activities Discussing outdoor activities, 'hill' indicates areas suitable for hiking or biking. We're biking up the hill this weekend. Pro Tip 3/3Describing landscapes 'Hill' can elucidate the nature of an area's terrain in descriptions. Quaint cottages dotted the rolling hills.