rucksack [M19th] This is an adoption of a southern German word, literally a ‘back sack’. Haversack [E18th] also comes, via French, from German, from hafersack ‘bag for horse oats’, which was originally a military term. Also German is knapsack [E17th] coming via Dutch, from Knappesack from knappe ‘bite, food’ and zak ‘sack’.