“Digression (noun): A turning aside or straying from the main discourse or topic; departure from the theme; excursive passage. Adjective: digressive, digressional; adverb: digressively; verb: digress.
‘He got a D plus because they kept yelling “Digression!” at him all the time. For instance, he made this speech about this farm his father bought in Vermont. They kept yelling “Digression!” at him the whole time he was making it, and his teacher, Mr. Vinson, gave him an F on it because he hadn’t told what kind of animals and vegetables and stuff grew on the farm and all.’” J.D. Salinger, The Catcher in the Rye
Excerpted from: Grambs, David. The Random House Dictionary for Writers and Readers. New York: Random House, 1990.