Definitions for "Coinsurance"
Insurance jointly with another or others; specif., that system of fire insurance in which the insurer is treated as insuring himself to the extent of that part of the risk not covered by his policy, so that any loss is apportioned between him and the insurance company on the principle of average, as in marine insurance or between other insurers.
Aa clause in an insurance policy stating the minimum percentage of value to be insured in order to collect the full amount of loss.
The cost sharing part of your bill that you have to pay.