knapsack
noun [ C ] UK old-fashioned or US uk/ˈnæp.sæk/ us/ˈnæp.sæk/
（徒步旅行者或登山者用的帆布或皮制的）小背包
a bag carried on the back or over the shoulder, used especially by people who go walking or climbing for carrying food, clothes, etc.
Compare: rucksackhaversack backpack noun