prune, popular name for a dried plum. Fruits of the many varieties of Prunus domestica, which are firm-fleshed and dry easily without removal of the stone, are gathered after falling from the tree, dipped in lye solution to prevent fermentation, dried in the sun or in kilns, and then "glossed" with a steam, glycerin, or fruit-juice bath to produce a sterile, glossy skin. Most of the commercial product comes from the Pacific coast states. A type of prune was used by Native Americans as a staple item of diet.