late 13c., possibly from Old French fi, exclamation of disapproval (12c.), and reinforced by Old Norse fy or some other Scandinavian form; it's a general sound of disgust that seems to have developed independently in many languages. Fie-fie was a 19c. British jocular word for "improper," also, as a noun, "woman of tarnished reputation" [OED].
updated on November 06, 2014