A sugar plum is a piece of dragée or hard candy made of hardened sugar in a small round or oval shape."Plum" in the name of this confection does not mean plum in the sense of the fruit of the same name. According to The Atlantic Monthly, traditional sugar plums contained no fruit, but were hardened sugar balls. According to the Huffington Post, these hardened sugar balls were comfits, and often surrounded a seed, nut, or spice.