1. Referring to something that is not fixed but which can be established or changed with bargaining and compromises: James was trying to arrange a negotiable salary agreement based on his education and experience.
2. Capable of being traversed, dealt with, or accomplished: Pete had to drive on a difficult but negotiable road before he could reach his destination.

Something that cannot be changed by discussion: Ted was told that if he signs the contract, the terms would be non-negotiable; so, he had better be sure that he understands the legal limits before he commits himself to it.