1 the book | Definition of the book

the book

noun

Definition of the book

US, informal
1 : the knowledge or information that relates to a particular subject, person, etc. The book on him is that he can't hit a curveball.
2 : a book that lists the names, addresses, and phone numbers of the people and businesses in a certain area : telephone book Give me a call if you need to. I'm in the book.