Definition - What does All-Risk Policy mean?
An all-risks policy is insurance coverage that insures against all possible property casualties, except for specifically excluded risks. It contrasts with named perils coverage, which protects only against listed perils. Because "all" implies broader coverage than the reality, the term is no longer widely used. Many in the industry have switched to using "open perils" or "special perils."
An all-risk policy is also known as open perils or special perils coverage.
Insuranceopedia explains All-Risk Policy
For example, an all-risks homeowner's policy that does not list flood as an exclusion would cover damages arising from a flood. As it is the most comprehensive kind of policy, it is the most expensive. Insurance companys calculate or determine the cost in reference to the likelihood of the claim arising.