NOUN (2)

1. mountains in southwestern South Dakota and northeastern Wyoming; sacred to the Sioux (whites settling in the Black Hills led to the Battle of Little Bighorn); site of Mount Rushmore;

2. mountains in western South Dakota and northeastern Wyoming;

WordNet (r) 3.0 (2006):

Black Hills
    n 1: mountains in southwestern South Dakota and northeastern
         Wyoming; sacred to the Sioux (whites settling in the Black
         Hills led to the Battle of Little Bighorn); site of Mount
         Rushmore
    2: mountains in western South Dakota and northeastern Wyoming