[bohl-sohn] 
| a desert valley, the level of which has been raised by aggradation, usually draining into a playa. |
| bol·son (bōl-sōn') n. Chiefly Southwestern U.S. A flat arid valley surrounded by mountains and draining into a shallow central lake. [American Spanish bolsón, augmentative of Spanish bolsa, purse, pouch, from Late Latin bursa; see bursa.] |