- a bag or satchel used especially by a student for carrying books.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for book bag
But he forgot that he had left his book-bag lying in the street.
Then his mamma asked, "How came you to put your book-bag on the step?"
Then Susan looked, and Harry looked; but the book-bag was not there.
A book-bag or haversack, strapped around your shoulders, will also be a convenience.Our Bird Comrades
Leander S. (Leander Sylvester) Keyser
So she called Susan, and asked her to go up the street with Harry to look for his book-bag.