Flump is a verb that means to sit or fall down heavily.
The origin or our word of the day is unclear, but it seems to be imitative in nature, in other words, flump seems to have come from an attempt to imitate the sound of someone or something falling onto something. Here’s an example of flump in use:
I was so exhausted after the race that I was afraid I’d flump to the ground after crossing the finish line. Luckily I didn’t fall down until I got to my car seat.