mutual
adj.adj. shared by two or more people. If you and a friend both like the same music, you have a mutual interest.
adj. held in common by two or more parties; experienced or done by each of two or more parties toward the other.
The two companies reached a mutual agreement.
They decided to end their relationship by mutual consent after realizing they wanted different things.
The success of the partnership relied on mutual respect and a shared vision for the future of the technology sector.
Borrowed from Middle French mutuel, from Latin mūtuus.
Commonly used in the phrase 'mutual friend' to describe someone known by two people who do not necessarily know each other well.
We have a common friendWe have a mutual friendWhile 'common' means shared, 'mutual friend' is the standard idiomatic expression for a shared acquaintance.