land bridge

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A neck of land that connects two landmasses; an isthmus.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun in biogeography: an isthmus or other land connection between what at other times are separate land masses
• noun Ireland, UK, travel terminology Travel by ferry from one country, via another country by road, then by another ferry crossing to a third country. An example is from Ireland by ferry to the UK, by road to the opposite coast, then ferry to France.