n. 共同保险

[ noun ]
insurance issued jointly by two or more underwriters
<noun.possession>

Coinsurance \Co`in*sur"ance\, n. [Co- + insurance.]
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.
[Webster 1913 Suppl.]