a canyon with steep side walls terminating headwards in a vertical cliff.
Origin of box canyon
An Americanism dating back to 1870–75
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for box canyon
Western US a canyon with vertical or almost vertical walls
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012