The partially dried fruit of any of several varieties of the common plum, Prunus domestica. Any kind of plum that can be dried without spoiling. Slang An ill-tempered, stupid, or incompetent person. Slang To make a facial expression exhibiting ill temper or disgust: "Their faces prune at the slightest provocation\u201d ( James Wolcott). To cut off or remove dead or living parts or branches of (a plant, for example) to improve shape or growth. To remove or cut out as superfluous. To reduce: prune a budget. To remove what is superfluous or undesirable.