knapsack: [17] The -sack of knapsack is no doubt essentially the same word as English sack, but the knap- presents slightly more of a problem. The term was borrowed from Low German knappsack, and so probably knapprepresents Low German knappen ‘eat’ – the bag having originally been named because it carried a traveller’s supply of food. [knapsack etymology, knapsack origin, 英语词源]