IPA: /ˈbʊkˌbæɡ/
KK: /ˈbʊkˌbæɡ/
A bag used to carry books and other school supplies.
She packed her bookbag with all the textbooks she needed for class.
The word 'bookbag' is formed from 'book' (from Old English 'bōc', meaning a written work or text) and 'bag' (from Old Norse 'baggi', meaning a sack or pouch). A bookbag is essentially a bag designed to carry books.
Think of a 'written work' ('book') being carried in a 'sack' ('bag') — that's what a bookbag is for.
No commonly confused words.