1. To freefall down to some lower place or level from a high place or position. He teetered precariously on the edge of the building before plummeting to the ground. I stood watching in horror as the vase with my grandfather's ashes came plummeting down to the floor from the mantelpiece.

2. To suffer a very sudden, severe drop down to some lower position of value, esteem, success, etc. The company's stock plummeted down to its lowest level in nearly two decades. After a brief stint in the top ten of the billboards chart, the band's new album plummeted to number 75 in its second week.