Source : Webster's Revised Unabridged Dictionary (1913)

Plum \Plum\, n.
   Something likened to a plum in desirableness; a good or
   choice thing of its kind, as among appointments, positions,
   parts of a book, etc.

Plum \Plum\, n. [AS. pl[=u]me, fr. L. prunum; akin to Gr. ?, ?.
   Cf. {Prune} a dried plum.]
   1. (Bot.) The edible drupaceous fruit of the {Prunus
      domestica}, and of several other species of {Prunus};
      also, the tree itself, usually called {plum tree}.

            The bullace, the damson, and the numerous varieties
            of plum, of our gardens, although growing into
            thornless trees, are believed to be varieties of the
            blackthorn, produced by long cultivation. --G.
                                                  Bentham.

Source : WordNet®

plum
     adv 1: exactly; "fell plumb in the middle of the puddle" [syn: {plumb}]
     2: completely; used as intensifiers; "clean forgot the
        appointment"; "I'm plumb (or plum) tuckered out" [syn: {clean},
         {plumb}]

plum
     n 1: any of several trees producing edible oval smooth-skinned
          fruit with a single hard stone [syn: {plum tree}]
     2: any of numerous varieties of small to medium-sized round or
        oval smooth-skinned fruit with a single pit

Source : Free On-Line Dictionary of Computing

PLUM
     
        A {compiler} for a substantial subset of {PL/I} for the
        {Univac 1100}, from the {University of Maryland}.
     
        ["PL/I Programming with PLUM", M.V. Zelkowitz, Paladin House,
        1978].
     
        (1995-02-23)