CONCORDAT
covenant, compact, concordat
(noun) a signed written agreement between two or more parties (nations) to perform some action
Source: WordNet® 3.1
Etymology
Noun
concordat (plural concordats)
A formal agreement between two parties, especially between a church and a state; specifically, an agreement between the Pope and a government.
Source: Wiktionary
Con*cor"dat, n. Etym: [F. concordat, L. concordato, prop. p. p. of
concordare. See Concord.]
1. A compact, covenant, or agreement concerning anything.
2. An agreement made between the pope and a sovereign or government
for the regulation of ecclesiastical matters with which both are
concerned; as, the concordat between Pope Pius VIL and Bonaparte in
1801. Hook.
Source: Webster’s Unabridged Dictionary 1913 Edition