Grimoire
This is a spellbook – a mythical textbook of magic. The etymology is not clear.
Why I Looked It Up
In an article about programming:
I went to the Borders bookstore in the Short Hills mall and bought “Beginning Visuall C++” by Ivor Horton. It ran to twelve hundred pages – my first grimoire.
I also saw many references to the fictional Necronomicon, by H.P. Lovecraft.
Finally, while walking through Barnes and Noble, I saw a gaming book called Grimoire Nier. Not sure what it was about – something to do with magic.