by . by or in my book {adv. phr.} In my opinion; as far as I am concerned; in my judgment. By my book, Mr. Murgatroyd is not a very good department head. Categories: add yours {adv. phr.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2025 To section: B Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Add my comment