Haaversack

Part of speech: noun

Definitions

1. A canvas or cloth bag worn by soldiers to carry food, ammunition, and personal necessities during marches or campaigns
2. A pouch slung over the shoulder by military personnel to hold rations, ammunition, and other gear needed in the field
3. A soldier's carrying bag for provisions and equipment, typically worn across the body as part of standard military kit

Etymology: The word comes from German "Habersack," a compound of "Haber" (oats) and "Sack" (bag). It originally named a bag for carrying oats, usually for horses or travelers. The sense then shifted to a shoulder bag for carrying food and small items, and soldiers in particular adopted it for rations. French took the word as "havresac," and English later borrowed it from there. The double "a" in your spelling is a common slip. The standard form is "haversack," and the oat origin is still visible in its first syllables.