To plunk means to drop or set something down heavily and carelessly, often making a dull thud. When you come home exhausted and plunk your backpack on the floor, you're not placing it gently: you're letting it fall with a satisfying thump. A tired musician might plunk down on the piano bench after a long rehearsal.

The word captures both the sound and the feeling of the action. It's heavier than “place” but less violent than “slam.” When you plunk yourself into a chair, you're collapsing into it without ceremony, maybe after a long day at school.

Plunk can also be a noun for a hollow, twanging sound, like when you plunk a single string on a guitar without really playing it, or when a pebble goes plunk as it drops into a pond. The word itself sounds like what it describes: short, blunt, and final.