when two or more insurers share a particular risk:
• Under co-insurance, private brokers assume 20% of the risk in insuring mortgages for multi-family apartment blocks, and the federal government is responsible for the remainder.
— co-insurer noun [countable]
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co-insurance UK US (also coinsurance) noun [ U] INSURANCE
► a situation in which two or more insurance companies share a risk
► in the US, a system of health insurance in which the patient pays a percentage of the cost of their treatment: »
We've also seen employers moving away from copayment to coinsurance plans.
co-insurer (also coinsurer) noun [C]
Financial and business terms. 2012.