be an open book

be an open book

1. To be easy to understand or decipher. I wish these legal contracts were an open book.
2. To act (or purport to act) honestly, with no secrets. Ask me anything, I'm an open book. Adam says he's an open book, but I've seen him sneaking out of his house late at night.
See also: book, open
References in periodicals archive ?
OAKLAND - The Lakers' lives will soon be an open book.