1560s, past participle adjective from gild, v.. Late Old English had gegylde; Middle English had gilden (adj.). In modern use the more dignified past participle of gild, alternative to gilt. Shakespeare's lilies were never gilded; the quote ("King John," iv.2) is, "To gild refined gold, to paint the lily." Gilded Age as an era in U.S. history (roughly 1870-1900) is from the novel "The Gilded Age" by Mark Twain and Charles Dudley Warner, published in 1873.