The Collaborative International Dictionary of English v.0.48:

Pourparler \Pour`par`ler"\, n. [F.] (Diplomacy)
   A consultation preliminary to a treaty.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

POURPARLER, French law. The conversations and negotiations which have taken
place between the parties in order to make an agreement. These form no part
of the agreement. Pard. Dr. Com. 142.
     2. The general rule in the common law is the same, parol proof cannot,
therefore, be given to contradict, alter, add to, or diminish a written
instrument, except in some particular cases. 1 Dall. 426; Dall. 340; 8 Serg.
& Rawle, 609; 7 Serg. Rawle, 114.