what is a plum
plum - any of numerous varieties of small to medium-sized round or oval fruit having a smooth skin and a single pit. genus Prunus, Prunus - a genus of shrubs and trees of the family Rosaceae that is widely distributed in temperate regions. wild plum, wild plum tree - an uncultivated plum tree or shrub. common plum, Prunus domestica - any of various widely distributed plums grown in the cooler temperate areas.