counterletter n in the civil law of Louisiana: a secret agreement that expresses the true intent of the parties to a simulation; esp: a writing embodying the agreement
counterletter can have no effects against third persons in good faith — Louisiana Civil Code
◇ An agreement stating that the conveyor of some land is still the owner, even though the other party has been given a bill of sale, is an example of a counterletter.
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.