9cff82d2__Your_Indispensable_Guide_TIME__What_it_is
[Term] The Underinsured [Why it matters] The underinsured aren't likely to stave off development of chronic diseases, since they often don't receive routine medical care. In the end, this means their health-care costs are higher than those who are fully insured. They also face the threat of medical bankruptcy, despite being technically insured. [What it is] 
People with, for example, catastrophic health insurance (see definition) but who still face the threat of high medical bills and who are just as likely as the uninsured to forgo services like preventive care. The underinsured also include people who have relatively low caps for insurance, meaning their insurers will pay only a preset annual amount (any expenses beyond that will not be reimbursed). Research suggests that as many as 25 million Americans are underinsured.
Understanding the Health-Care Debate: Your Indispensable Guide-TIME
What it is