Which term describes the main land mass of a continent or country?

The term that accurately describes the main land mass of a continent or country is "mainland." This term specifically refers to the principal area of land that constitutes the majority surface of a continent, distinguishing it from smaller landforms and coastal regions.

In contrast, a peninsula refers to a landform that is surrounded by water on the majority of its sides but is still connected to the mainland via an isthmus. An archipelago is a group or chain of islands, which does not represent a single land mass. A delta, on the other hand, is a landform created by sediment deposits at the mouth of a river, also differing significantly from the broader concept of a mainland. Understanding these definitions clarifies why "mainland" is the most suitable term for the main land mass of a continent or a country.