Posset/ˈpɑːsɪt/ Definition 1 of 2Pro Tip 1/3Historical Drink Posset is an old-fashioned drink, mostly found in historical contexts or literature. In the novel, characters sipped posset by the fireplace. Pro Tip 2/3Rarely Used It's rarely used in modern English, so it might be unfamiliar to contemporary listeners. When he mentioned posset, the students looked confused. Pro Tip 3/3Medicinal Qualities Historically, posset was thought to have medicinal qualities and was given to the sick. He prepared a posset for her, hoping to ease her cold.