Final answer:
A policy covering a specific serious or life-threatening condition is called a critical illness plan, dread disease policy, or specified disease policy, but not an obscure disease policy.
Step-by-step explanation:
A policy that covers one specific type of life-threatening or serious condition is known by several names, including a critical illness plan, a dread disease policy, and a specified disease policy. However, the term 'obscure disease policy' is not commonly used for this type of insurance and is not one of the known names for such a policy. Such policies are designed to provide financial protection against the economic impacts of certain severe health conditions.