リュックサック
also: リュックザック · ルックサック · ルックザック
Usage patterns
リュックサックを背負うto carry a backpack on one's back
He walked along the mountain trail carrying a large backpack on his back.
リュックサックに〈物〉を入れるto put something into a backpack
I put water and food into my backpack.
リュックサックを下ろすto take off/set down a backpack
Since I was tired, I took off my backpack and rested.