early 15c., from Middle French ambre gris "gray amber" (see amber), "a wax-like substance of ashy colour, found floating in tropical seas, a morbid secretion from the intestines of the sperm-whale. Used in perfumery, and formerly in cookery" [OED]. Its origin was a mystery in Johnson's day, and he records nine different theories. King Charles II's favorite dish was said to be eggs and ambergris [Macauley, "History of England"]. French gris is from Frankish *gris or some other Germanic source (cognates: Dutch grijs, Old High German gris; see gray).