a framework, usually of lightweight metal tubing, that supports a backpack on the wearer, often by curved extensions that fit over the shoulders.
Origin of packframe
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
mountaineering a light metal frame with shoulder straps, used for carrying heavy or awkward loads
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