A Wiccan book of rituals, spells and magickal lore. Once hand copied upon initiation, the BOS is now photocopied or typed in some covens. No one "true" BOS exists; all are relevant to their respective users.
A term for a collection of information in book form that a Witch uses for reference. Much akin to a "Magickal cook book." Some say the term derived from the practice during the burning times of hiding any Magickal books from persecution - thus "in the shadows." Another name for a BOS is grimoire.
A Wiccan term which has been adopted by many neo-pagans. This book is a combination Magickal diary, and recipe book. In addition, it will typically contain rituals, spells, beliefs, and the like.