plum [OE] Latin prunum is the source of both plum and prune [LME], a plum preserved by drying. The change from pr- to pl- is not an unusual one. The ‘l’ and ‘r’ are made in very similar parts of the mouth, and some languages do not distinguish between the two sounds. Plum pudding [M17th] was originally made with plums. The use of plum to refer to something highly desirable, ‘the pick of the bunch’, probably arose from the idea of picking the tastiest bits out of a plum pudding. Upper-class people are sometimes said to have a plum in the mouth, or to speak with a plummy voice [M19th]. The idea of having a plum in the mouth goes right back to the 1530s, though at first it meant that the speech was indistinct rather than posh.