Clement XIV: Sede Vacante Coin from 1774, Reverse
Clement XIV: Sede Vacante Coin from 1774, ObverseSede vacante is Latin for, The seat is open, meaning the time between the death of one pope and the election of the next one.
In this case it is the time between the death of Clement XIV, 1769-1774, and the election of Pius VI, 1775-1799.