coinsurance

noun

co·​in·​sur·​ance ˌkō-ən-ˈshu̇r-ən(t)s 

also -ˈin-ˌshu̇r-

1

: joint assumption of risk (as by two underwriters) with another

2

: insurance (such as fire insurance) in which the insured is obligated to maintain coverage on a risk at a stipulated percentage of its total value or in the event of loss suffer a penalty in proportion to the deficiency

3

: health insurance in which the insured is required to pay a fixed percentage of the cost of medical expenses after the deductible has been paid and the insurer pays the remaining expenses

Coinsurance is not a new idea—Americans who grew up in the era before managed care will remember their parents paying 20% of the costs of office visits, tests, and prescriptions.

—Thomas H. Lee et al.

Examples of coinsurance in a Sentence

Recent Examples on the Web

The best approach is to stop the accumulation of new medical debt at the source by expanding health insurance coverage and reducing deductibles and coinsurance. —Jasmine Laws, MSNBC Newsweek, 30 Nov. 2025

Federal taxpayers fund much of Medicare, but beneficiaries also must pay copays and coinsurance. —NPR, 26 Nov. 2025

With deductibles, coinsurance and copayments adding up quickly, one major medical event could devastate your savings. —Angelica Leicht, CBS News, 24 Nov. 2025

Nibbles also offers the ability to customize your policy via add-ons, such as take-home prescriptions, physical therapy, higher coinsurance (up to 90%), lower deductible and more. —Ryley Amond, CNBC, 12 Oct. 2025

Word History

First Known Use

circa 1889, in the meaning defined at sense 1

Rhymes for coinsurance

• concurrence
• deterrence
• incurrence
• occurrence
• recurrence
• transference
• countertransference

Medical Definition

coinsurance

noun

co·​in·​sur·​ance ˌkō-ən-ˈshu̇r-ən(t)s, -ˈshər- also -ˈin-ˌshu̇r-, -ˌshər- 

: health insurance in which an insurer requires the insured to pay a fixed percentage of the cost of medical expenses after the deductible has been paid and with the insurer to pay the remaining expenses

Coinsurance is not a new idea—Americans who grew up in the era before managed care will remember their parents paying 20% of the costs of office visits, tests, and prescriptions.

—Thomas H. Lee et al., The New England Journal of Medicine

Legal Definition

coinsurance

noun

co·​in·​sur·​ance ˌkō-in-ˈshu̇r-əns, kō-ˈin-ˌshu̇r- 

1

: joint assumption of risk (as by two underwriters) with another

2

: insurance (as fire insurance) in which the insured is obligated to maintain coverage on a risk at a stipulated percentage of its total value or in the event of loss to suffer a penalty in proportion to the deficiency