oil [ME] The English word oil goes back to Latin oleum, which referred especially to *olive oil. If someone sits up writing or reading until very late they are burning the midnight oil [M17th], an expression looking back to the days when the main source of artificial light would be an oil lamp. Oil paints are traditionally used for portraits, and since the early 20th century the unkind verdict that someone is no oil painting [E20] has been a way of saying that they are not attractive. In classical times, there was a belief among seamen—recorded by the Roman statesman and scholar Pliny the Elder (ad 23–79)—that pouring oil into a stormy sea could calm the waves. This is probably what lies behind the proverbial expression pour oil on troubled waters, meaning to try to settle a disagreement by soothing those involved. The opposite is to add oil to the fire [M16th], to make something worse.