mochila
/moˈt͡ʃila/ · B1 · noun · f
backpack
🎒 From Basque mutil (boy): the bag the errand boy carried
A mochil was an errand boy, a word from Basque mutil, meaning boy. The mochila was the sack of supplies he carried on his back, so a schoolbag is the errand boy's bag.