pruneyoudaoicibaDictYouDict[prune 词源字典]
prune: English has two distinct words prune. The older, ‘dried plum’ [14], is ultimately the same word as plum, and indeed in the 16th and 17th century was often used for ‘plum’. It comes via Old French prune from Vulgar Latin *prūna, which also gave English (through Germanic) plum. Prune ‘cut off unneeded parts’ [15] denotes etymologically ‘cut in a rounded shape in front’. It comes via Old French proignier from Vulgar Latin *prōrotundiāre, a compound verb formed from the Latin prefix prō- ‘in front’ and rotundus ‘round’ (source of English rotund and round).
=> plum; rotund, round[prune etymology, prune origin, 英语词源]
prune (n.)youdaoicibaDictYouDict
mid-14c., "a plum," also "a dried plum" (c. 1200 in place name Prunhill), from Old French pronne "plum" (13c.), from Vulgar Latin *pruna, fem. singular formed from Latin pruna, neuter plural of prunum "a plum," by dissimilation from Greek proumnon, from a language of Asia Minor. Slang meaning "disagreeable or disliked person" is from 1895. Prune juice is from 1807.
prune (v.)youdaoicibaDictYouDict
early 15c., prouyne, from Old French proignier "cut back (vines), prune" (Modern French provigner), of unknown origin. Perhaps [Watkins] from Gallo-Roman *pro-retundiare "cut in a rounded shape in front," from pro- "forth" (see pro-) + *retundiare "round off," from Latin rotundus (see round (adj.)). Klein suggests the Old French word is from provain "layer of a vine," from Latin propago (see prop (n.1)).

Or the Middle English word might be identical with the falconry term proinen, proynen "trim the feather with the beak" (late 14c.), source of preen [Barnhart]. Related: Pruned; pruning. Pruning hook is from 1610s; pruning knife from 1580s.