in the ecclesiastical law, the trust or administration of the revenues of a benefice, given either to a layman, to hold by way of depositum for six months, in order to repairs, &c. or to an ecclesiastic or beneficed person, to perform the pastoral duties thereof, till once the benefice is provided with a regular incumbent.
Anciently the administration of vacant bishoprics belonged to the nearest neighbouring bishop; which is still practised between the archbishopric of Lyons and the bishopric of Autun: on this account they were called commendatory bishops.
This custom appears to be very ancient. S. Athanasius COM
Commendam, Commendatus.
Nasius says of himself, according to Nicephorus, that there had been given him in commendam, i.e., in administration, another church besides that of Alexandria whereof he was stated bishop.
The care of churches, it seems, which had no pastor, was committed to a bishop, till they were provided of an ordinary: the register of Pope Gregory I. is full of these commissions, or commendams, granted during the absence or sickness of a bishop, or the vacancy of the see.
Some say, that Pope Leo IV. first set the modern commendams on foot, in favour of ecclesiastics who had been expelled their benefices by the Saracens; to whom the administration of the vacant churches was committed for a time, in expectation of their being restored; though S. Gregory is said to have used the same, while the Lombards defoliated Italy.
In a little time the practice of commendams was exceedingly abused; and the revenues of monasteries given to laymen for their subsistence. The bishops also procured several benefices, or even bishoprics, in commendam, which served as a pretext for holding them all without directly violating the canons. Part of the abuse has been retrenched; but the use of commendams is still retained as an expedient to take off the incompatibility of the person by the nature of the benefice.
When a person is made bishop, his patronage becomes vacant; but if the king give him power, he may still hold it in commendam.