pact
pact (pakt) , noun
[Latin pactum, from paciscere to make a bargain or contract, from pacere to settle, or agree upon; compare pangere to fasten, Greek phgny`nai, Sanskrit pāca bond, and English fang: compare French pacte. Compare Peace, Fadge, v.]
An agreement; a league; a compact; a covenant. — Bacon
The engagement and pact of society which goes by the name of the constitution.