plump1
  
  adj.
 full and rounded in shape. 
▸(of a person) rather fat.
v.
 
(
often plump something up)
 make or become full and round.
Derivative
  
    - plumpish adj.
- plumply adv.
- plumpness n.
- plumpy adj.
 
  Etymology
  C15 (in the sense ‘blunt, forthright’): rel. to MDu. plomp, Mid. Low Ger. plump ‘blunt, obtuse’.
 
  
    
plump2
  
  v.
  - 
(often plump something down)
 set or sit down heavily or unceremoniously.
- 
(plump for)
 decide definitely in favour of (one of two or more possibilities).
n.
 archaic an abrupt plunge or heavy fall.
adv.
 informal  - with a sudden or heavy fall.
- dated directly and bluntly.
Etymology
  ME: rel. to Mid. Low Ger. plumpen, MDu. plompen ‘fall into water’, prob. of imitative origin.