The Collaborative International Dictionary of English v.0.48:
Prune \Prune\, n. [F. prune, from L. prunum a plum. See Plum.]
A plum; esp., a dried plum, used in cookery; as, French or
Turkish prunes; California prunes.
German prune (Bot.), a large dark purple plum, of oval
shape, often one-sided. It is much used for preserving,
either dried or in sirup.
Prune tree. (Bot.)
(a) A tree of the genus Prunus (Prunus domestica), which
(b) The West Indian tree, Prunus occidentalis.
South African prune (Bot.), the edible fruit of a
sapindaceous tree (Pappea Capensis).