The word munificence comes from the Latin mūnificentia, which derives from mūnificus, meaning “bountiful” or “generous.” This, in turn, is formed from mūnus (“gift, duty, service”) and -ficus (a suffix meaning “making” or “doing,” related to facere, “to make or do”).
Thus, munificence originally carried the sense of “performing a duty of generosity”—giving as a noble or moral obligation rather than mere charity. The word entered English in the late 16th century, retaining this connotation of great generosity, particularly from a benefactor or patron.