The Collaborative International Dictionary of English v.0.48:

Plump \Plump\, n.
   A knot; a cluster; a group; a crowd; a flock; as, a plump of
   trees, fowls, or spears. [Obs.]
   [1913 Webster]

         To visit islands and the plumps of men.  --Chapman.
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The Collaborative International Dictionary of English v.0.48:

Plump \Plump\, v. i. [Cf. D. plompen, G. plumpen, Sw. plumpa,
   Dan. plumpe. See Plump, a.]
   1. To grow plump; to swell out; as, her cheeks have plumped.
      [1913 Webster]

   2. To drop or fall suddenly or heavily, all at once."Dulcissa
      plumps into a chair." --Spectator.
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   3. To give a plumper. See Plumper, 2.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Plump \Plump\, v. t. [imp. & p. p. Plumped; p. pr. & vb. n.
   Plumping.]
   1. To make plump; to fill (out) or support; -- often with up.
      [1913 Webster]

            To plump up the hollowness of their history with
            improbable miracles.                  --Fuller.
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   2. To cast or let drop all at once, suddenly and heavily; as,
      to plump a stone into water.
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   3. To give (a vote), as a plumper. See Plumper, 2.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Plump \Plump\ (pl[u^]mp), a. [Compar. Plumper
   (pl[u^]mp"[~e]r); superl. Plumpest.] [OE. plomp rude,
   clumsy; akin to D. plomp, G., Dan., & Sw. plump; probably of
   imitative origin. Cf. Plump, adv.]
   1. Well rounded or filled out; full; fleshy; fat; as, a plump
      baby; plump cheeks. --Shak.
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            The god of wine did his plump clusters bring. --T.
                                                  Carew.
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   2. Done or made plump, or suddenly and without reservation;
      blunt; unreserved; direct; downright.

            After the plump statement that the author was at
            Erceldoune and spake with Thomas.     --Saintsbury.
      [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Plump \Plump\, adv. [Cf. D. plomp, interj., G. plump, plumps.
   Cf. Plump, a. & v.]
   Directly; suddenly; perpendicularly. "Fall plump." --Beau. &
   Fl.
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WordNet (r) 3.0 (2006):

plump
    adv 1: straight down especially heavily or abruptly; "the anchor
           fell plump into the sea"; "we dropped the rock plump into
           the water"
    adj 1: sufficiently fat so as to have a pleasing fullness of
           figure; "a chubby child"; "pleasingly plump"; [syn:
           chubby, embonpoint, plump]
    n 1: the sound of a sudden heavy fall
    v 1: drop sharply; "The stock market plummeted" [syn: plummet,
         plump]
    2: set (something or oneself) down with or as if with a noise;
       "He planked the money on the table"; "He planked himself into
       the sofa" [syn: plank, flump, plonk, plop, plunk,
       plump down, plunk down, plump]
    3: make fat or plump; "We will plump out that poor starving
       child" [syn: fatten, fat, flesh out, fill out,
       plump, plump out, fatten out, fatten up]
    4: give support (to) or make a choice (of) one out of a group or
       number; "I plumped for the losing candidates" [syn: plump,
       go]