Flamboyant; adjective; strikingly bold or brilliant.

From “The Yellow Wallpaper” by C.P. Gillman. “One of the most sprawling flamboyant patterns committing every artistic sin.” (second page)

In this passage, the narrator is describing the wallpaper that she encountered in the nursery room, where she was going to be sleeping in. She didnt like the aspect of the wallpaper, nor the design. To her, it was strikingly brilliant in a negative way, not a good brilliant.