Fatuity- Something foolish or stupid
“Looked at in one way each breadth stands alone, the bloated curves and flourishes—a kind of “debased Romanesque” with delirium tremens—go waddling up and down in isolated columns of fatuity.” -The Yellow Wallpaper
Much of this story goes into detail describing the environment, many of these descriptions being heavily opinionated based on the context. There is an immense obsession over the wallpaper, thoughts going back and forth over it’s design. Fatuity in this case is being used to describe how strange, even nonsensical the wallpapers design is.