The term 'bookish sort' can be defined by two crossword solutions: NERD (4 letters) and PEDANT (6 letters). A NERD is someone who is socially awkward, highly intelligent, and passionate about a particular subject. They often have an encyclopedic knowledge of their chosen field. A PEDANT is someone who is overly concerned with details and rules, often to the point of being annoying. Both terms are often used to describe someone who is bookish and studious.