See: Aviation Unearned Premium INSURANCE.
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Insurance against loss by the insured of unearned premium due to payment of a claim made prior to the end of the term for which the premium was paid. A loss on the second day of a Policy written for a year would have the effect of being expenses over an eleven month period, during which time the Insurance Company would not be insuring the risks since the risk did not exist any longer and thus it would be unearned.