gravy: [14] To begin with, the word gravy signified a sort of spiced stock-based sauce served with white meat; it was not until the 16th century that its modern sense ‘meat juices’ or ‘sauce made from them’ emerged. Its origins are problematical. It is generally agreed that its v represents a misreading of an n in the Old French word, grané, from which it was borrowed (modern v was written u in medieval manuscripts, and was often very hard to distinguish from n); but what the source of grané was is not clear.
The favourite candidate is perhaps grain (source of English grain), as if ‘sauce flavoured with grains of spice’, but graine ‘meat’ has also been suggested. => grain[gravy etymology, gravy origin, 英语词源]