A damson is a kind of plum. Like the plum, it comes from the Rosaceae family. Originally, the fruit comes from the Mediterranean. Damsons are thought to be members of the 'European Plum' family, which also includes greengage, mirabelle, quetsche, and Italian prune plums. The damson is generally less sweet than other kinds of plum and is used in jams, jellies, and liqueurs.