backsack

Compound of back +‎ sack, possibly influenced by backpack.

• (Received Pronunciation, General American) IPA^(key): /ˈbækˌsæk/
• Rhymes: -æksæk
• Hyphenation: back‧sack

backsack (plural backsacks)

1. A backpack.
   • 2012, Richard J. Sutcliffe, The Builder:

     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.

   • 2025, Josh Coker, Past The Fringe, page 27:

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

2. (slang, vulgar) The back of the testicles.

• “backsack”, in Urban Dictionary, launched 1999.