plump 1 
(plŭmp)
(plŭmp)adj. plump·er, plump·est
1. Well-rounded and full in form; chubby. See Synonyms at fat.
2. Abundant; ample: a plump reward.
v. plumped, plump·ing, plumps
v.tr.
To make well-rounded or full in form: plumped up the pillows.
v.intr.
To become well-rounded, chubby, or full in form: The baby plumped out at three months.
[Middle English, dull, probably from Middle Low German plomp, blunt, thick.]
plumpish adj.
plumply adv.
plumpness n.