Mainland is the main, largest part of a country or continent, as opposed to its islands. When people in Hawaii talk about the mainland, they mean the 48 connected states of the United States. When someone from Tasmania mentions the mainland, they're referring to the much larger landmass of Australia.

The word helps distinguish between a central territory and the smaller islands that belong to the same country. Alaska and Hawaii are both U.S. states, but only Alaska is physically connected to the mainland. Similarly, Great Britain is an island, but when British people refer to “the Continent” or mainland Europe, they mean the connected landmass across the English Channel.

Mainland can also describe the primary settled area versus outlying regions. In ancient Greece, mainland Greece was distinct from the Greek islands scattered throughout the Aegean Sea, even though Greek civilization flourished in both places.

The word suggests something substantial and central. When a business expands from an island to the mainland, it's usually moving to where more people live and more opportunities exist. The mainland isn't necessarily better, but it's typically larger, more connected, and easier to reach by land.