An agreement reached by means of mutual concession is called compromise.
A compromise, which term derived from Latin means "mutual promise", can be defined as a settlement in which the sides involved make a concession. The agreement resulting usually solves an issue in the best interest of everyone involved.
Example: Two business men want to have a meeting with each other but due to their busy schedules, they never seem to arrange the meeting. Subject "A" suggest to meet today at 5 P.M. but subject "B" prefers to meet at 6 P.M., and not earlier than that. The issue can be solved if they both arrange the meeting at 5:30 P.M., through a mutual concession in order to achieve an agreement. That is, they have to make a compromise.