coinsurance

noun3

1. •
   (US) The joint assumption of risk between the insurer and the insured party.
2. •
   The joint assumption of risk between multiple insurers.
3. •
   (US) The amount paid by the insured in accordance with this risk sharing.

   • For Part B-covered services, you usually pay 20% of the Medicare-approved amount after you meet your deductible. This is called your coinsurance. — 2021