What is an Electronics Databook?
A databook is a collection of datasheets, in printed book form, from a single manufacturer.  Sometimes manufacturers would include application notes or white papers in the databook as well. 

Back in "the day", engineers would have a large library of databooks.  Around 1997 my library was made from six 6-foot bookshelves completely full of databooks-- that used all the wall space in the employee break room.  Around the same time, manufacturer representatives and field-sales people from distributors would drive from customer to customer with their trunk full of databooks.  

This was before the Internet was useful, and PDF's were commonplace.  Databooks have been mostly obsoleted now, to the delight of field sales people and employees taking breaks everywhere.

Cookbooks are entirely different.  They were almost always published by third parties, not the chip manufacturers themselves, and thus were mostly manufacturer agnostic.  Cookbooks were more like application notes, while datasheets were more about formally documenting the manufacturers specifications.