mutual

Etymology

Borrowed from Middle French mutuel, from Latin mūtuus.

adj

1. Having the same relationship, each to each other.
   They were mutual enemies.
2. Collective, done or held in common.
   Mutual insurance.
3. Reciprocal.
   They had mutual fear of each other.
4. Possessed in common.
   They had been introduced by a mutual friend.
   On his area the pursuer built a dwelling-house, of which the gable and garden-wall were mutual with his neighbour Smith […] 1809, Faculty of Advocates (Scotland), Decisions of the Court of Sessions, from 1752 to 1808, page 216
5. (Relating to a company, insurance or financial institution) Owned by the members.

noun

1. A mutual fund.
2. (business, finance, insurance) A mutual organization.
3. (Internet) Either of a pair of people who follow each other's social media accounts.