In commendam

[1] The word commendam is the accusative singular of the Latin noun commenda, "trust", or "custody", which is derived from the verb commendare ("to entrust").

In a letter written around 379,[2] Ambrose mentions a church which he gave in commendam, while he was Bishop of Milan: "Commendo tibi, fili, Ecclesiam quae est ad Forum Cornelii ... donec ei ordinetur episcopus" ("I entrust unto thee, my son, the church which is at the Cornelian Forum ... until a bishop is allotted to it").

It also provided a steady income for whoever was nominated, and St. Gregory the Great (590–604) gave vacant monasteries in commendam to bishops who had been driven from their sees by the invading barbarians, or whose own churches were too poor to furnish them a decent livelihood.

[4] In the eighth century, the practice became widely abused when kings claimed the right to appoint abbots in commendam over monasteries, often nominating their own vassals, who were not monks but laymen, as a way of rewarding them.

The practice was open to abuse: favored cardinals began to receive multiple benefices, accepting them like absentee landlords, increasing their personal possessions to the detriment of the Church.