It's not clear to me that there is a rigorous definition of "continent", since different cultures enumerate them differently. For example, in the US, North Ame

It's not clear to me that there is a rigorous definition of "continent", since different cultures enumerate them differently. For example, in the US, North America and South America are counted separately, whereas in many cultures "America" is one continent (and, a related issue is that many people in Latin America would consider the US and Canada and NOT Mexico as part of "North America"). Also in some cultures Europe and Asia are separate, and in some they are one continent.