Sentence:  You are the reason I arrived "indecently" late at Madame de Volanges's and had all the old ladies thinking I was a <WSD>"Merveilleuse</WSD>". 
Meaning of the word marked with <WSD> tags:  A fashionable young Frenchwoman of the late 18th-century, characterized by extravagant dress sense and anti-revolutionary ideas.