overturn

To overturn is to reverse a decision, or to tip something over. A verdict, or a table.

The physical sense is the older one, and a car can overturn on a bend. The commoner modern use is legal and political, since a higher court overturns a conviction and a parliament overturns a veto. Both share the picture of something being turned upside down. It also describes upsets, so overturning a majority means winning where you were not expected to. The noun is an overturning, and turnover is a different word entirely.