I first heard the term "meta-novel" at a writer's conference in Tulsa, Oklahoma. The idea is that even though each book in a series stands alone, when read collectively they form one big ongoing novel about the main character. Each book represents its own arc: in book one of the series we meet the character and establish a meta-goal that will carry him through further books, in book two that meta-goal is tested, in book three - you get the picture.