(Italian: Piatto Cardinalizio)
An allowance granted by the pope to cardinals residing in the Curia or otherwise employed in the service of the Church, to defray their expenses.
This was called "the poor cardinal's plate."
The reason for the allowance is because when a cardinal is created, by that very fact he renounces his benefice or ecclesiastical pension unless an exception be made in his particular case.
The allowance made to cardinals today is very small.
New Catholic Dictionary