backsack

plural backsacks

1. A backpack.

   The cyborg slung a backsack over his shoulder and exited the cockpit.

   2025, Josh Coker, Past The Fringe, page 27

   1 more example

   A moment passed, then a bent old man labouring unsteadily under a backsack shuffled slowly through the afternoon gloom toward the Pawn shop's front entrance.

   2012, Richard J. Sutcliffe, The Builder

2. slangvulgarThe back of the testicles.