9cff82d2__Your_Indispensable_Guide_TIME__What_it_is
[Term] Actuarially Sound [Why it matters] Insurers now charge high premiums for small risk pools, like small businesses, to make sure they can cover whatever claims they might have to pay. This means, for example, if a business has 10 employees and one gets cancer, costing the insurer a lot, premiums for the whole group will be driven up. Health-reform proposals on the table could allow insurers to stay actuarially sound  without setting premium rates on the basis of pre-existing conditions  by forcing every American to get health insurance and allowing small groups and individuals to pool together through a health-insurance exchange (see definition). [What it is] 
An insurance plan that collects enough money in premiums to at least cover claims paid out.
Understanding the Health-Care Debate: Your Indispensable Guide-TIME
What it is