To fall quickly and without control. (Cambridge Dictionary)
To fall a lot in value in a short time. (Cambridge Dictionary)
To move in an uncontrolled was, as if falling or likely to fall. (Cambridge Dictionary)
To fall helplessly down, end over end, as by losing one’s footing, support, or equilibrium; plunge head long. (Dictionary.com)
To roll end over end, as in falling: (Dictionary.com)
To fall or decline rapidly; drop: (Dictionary.com)
If someone or something tumbles somewhere, they fall there with a rolling or bouncing movement. (Collins Dictionary)
Why do tumbleweeds tumble?
China and the word economy. Taking a tumble.