Douglas Harper's Etymology Dictionary
1870, "a rustling," from French (19c.), possibly imitative of the rustling of a dress. The word was popularized in English by a French play translated and given that name. Meaning "fussy details" is from 1876.
Wiktionary
a. frilly; heavily ornamental; fancy; overly elaborate, particularly as regards clothing. n. A rustling sound, as of silk fabric.
Wikipedia
Frou-Frou, is a French comedy film from 1955, directed by Augusto Genina, written by A. E. Carr, starring Dany Robin and Louis de Funès. The film is also known as "A Girl from Paris".
Usage examples of "frou-frou".
Only here and there the gentle frou-frou of a silk skirt, the rhythmic flutter of a fan, broke those few seconds' deadly, stony silence.
For a few moments, whilst Marguerite still stood there, puzzled and vaguely moved, she could hear the gentle frou-frou of the other woman's skirts against the soft sand of the path, and then a long-drawn sigh that sounded like a sob.
Chauvelin had sat through this ENTR’ACTE, with his eternal snuff-box in his hand, and with his keen pale eyes intently fixed upon a box opposite him, where, with much frou-frou of silken skirts, much laughter and general stir of curiosity amongst the audience, Marguerite Blakeney had just entered, accompanied by her husband, and looking divinely pretty beneath the wealth of her golden, reddish curls, slightly besprinkled with powder, and tied back at the nape of her graceful neck with a gigantic black bow.
Beyond, from the brilliant ball-room, the sweet notes of the gavotte, the frou-frou of rich dresses, the talk and laughter of a large and merry crowd, came as a strange, weird accompaniment to the drama which was being enacted here.