fie (interj.)youdaoicibaDictYouDict
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].
tarnish (v.)youdaoicibaDictYouDict
mid-15c. (transitive), from present participle stem of Middle French ternir "dull the luster or brightness of, make dim" (15c.), probably from Old French terne (adj.) "dull, dark," which according to Diez is from a Germanic source cognate with Old High German tarnjan "to conceal, hide," Old English dyrnan "to hide, darken," from Proto-Germanic *darnjaz (see dern), but there are difficulties of form, sense, and date. Intransitive sense from 1670s. Figurative sense is from 1690s. Related: Tarnished; tarnishing.