It means a certain type of expression
"<span>The novelty of the theme and its treatment enthralled the audience."
The Canterbury Tales dealt with themes that were not common for people to write about. At that time, people were starting to see the corruption of the church, so including that theme captivated them. Additionally, the characters came from a variety of backgrounds that people could relate to.</span>
A. The tittle of an essay
I'm not sure why though. All the different rules for English. Apologies if I get it wrong.
Misfit, misconstrue,misunderstand, misgiving, mischief... How many you need?