Real Dictionary

mutual insurance in American English
noun: insurance in which those insured become members of a company who reciprocally engage, by payment of certain amounts into a common fund, to indemnify one another against loss
noun: Mutual insurance is a system of insurance in which policyholders are company members.

mutual insurance in British English
noun: a system of insurance by which all policyholders become company members under contract to pay premiums into a common fund out of which claims are paid