WordWeb Online

1. Drop heavily
   - plonk down, plank down
    
2. Set (something or oneself) down with or as if with a noise
   "He plumped down the money on the table";
   - plank [informal], flump [informal], plonk [informal], plop, plunk, plunk down, plump, slap

Derived forms: plumps down

Type of: drop, place down, put down, set down