'Knapsack' definitions:

Definition of 'knapsack'

From: WordNet
noun
A bag carried by a strap on your back or shoulder [syn: backpack, back pack, knapsack, packsack, rucksack, haversack]

Definition of 'Knapsack'

From: GCIDE
  • Knapsack \Knap"sack`\, n. [D. knapzak; knappen to eat + zak a bag. See Knap, v. t., and Sack.] A case of canvas, leather, nylon, or other sturdy fabric, fitted with straps, for carrying on the back the food, clothing, or other supplies for a soldier or a traveler; as, to hike up the mountain with lunch in a knapsack. [1913 Webster +PJC]
  • And each one fills his knapsack or his scrip With some rare thing that on the field is found. --Drayton. [1913 Webster]