Pact (noun)

1. A formal agreement or treaty between countries or groups.
2. An agreement between two or more people or groups to do or not do something.

Origin:

Late middle english: from old french pacte, from latin pactum "something agreed", from the verb pacisci "make an agreement", from paciscere "to agree".

Examples:

1. The countries signed a pact to reduce their nuclear weapons.
2. The pact between the two companies was to share the profits.
3. The pact was made to keep the secret between the two friends.
4. The pact was made to stop the war between the countries.
5. The pact was not honored by one of the parties.