also: りゅっくざっく · るっくさっく · るっくざっく
noun
A bag carried on the back, often with two shoulder straps. The most common modern term for a backpack in Japanese.
from German Rucksack
旅行にはリュックサックが便利だ。
A backpack is convenient for traveling.
彼はリュックサック
He stuffed his textbooks into his backpack.