Here is the definition of an economic depression from Investopedia.
"In economics, a depression is commonly defined as an extreme recession that lasts three or more years or leads to a decline in real gross domestic product (GDP) of at least 10 percent."
My definition of an economic depression is based on Investopedia's definition.
I define an economic depression as at least a one-year decline in real GDP of 10% or more.
What is your definition?
If you are an economist, financier, banker, stock-market professional, etc., and you have your own definition please post it.