Derived from the Latin verb fidere . . .

Derived from the Latin verb fidere, “to trust" and related to foedus (“treaty"), the word federal had previously been used most commonly as a theological term that referred to the divine devolution of responsibility to human beings (i.e. the covenants whereby God made Abraham and Moses responsible for insuring that Israel worshiped the one and only God, and Christ responsible for redeeming humankind). In its secular context, a federal system was one in which the highest authority devolved power to subsidiary ones.

Hume refined the concept. He sought to combine the advantages of local accountability with those of a large state. . . . What was required, Hume concluded, was a system that left as much power as possible at the lower levels while investing as much as necessary in the higher ones.

Strobe Talbot, The Great Experiment: The Story of Ancient Empires, Modern States and the Quest for a Global Nation. (New York: Simon & Schuster, 2008), 92.