n. a sack of strong material used for carrying supplies, personal belongings, etc. when on the trail, usually carried on the back and supported by shoulder straps and, often, a tumpline.
1920  I note in the last issue . . . a good old-time packsack illustrated by Mr. Haines.
1926  Carcajou--the wolverine and glutton--stared at the pack-sack, then slid down and began tearing it. . . .
1960  These Nile men were rather the shanty-boy variety of Canadian riverman, just as much at home on certain Canadian rivers as Jean Baptiste had ever been but more skilled with the raft, the pike and the peavey than with the paddle and packsack.