Entry 2 senses · 2 variants Webster, 1913 backpack · back·pack · IPA /ˈbæk.pæk/ n. v. i. 01 n. a bag carried on the back, supported by straps looped over the shoulders. 1. a bag carried on the back, supported by straps looped over the shoulders. Syn. knapsack; rucksack; haversack. 02 v. i. to hike while carrying a backpack; -- often used in the form go backpacking; as, to backpack through the forest. 1. to hike while carrying a backpack; -- often used in the form go backpacking; as, to backpack through the forest. Also: go backpacking