Yucatán (or Yucatan) Peninsula

or Yucatan

1. peninsula comprising SE Mexico, Belize, & part of W Guatemala: it separates the Gulf of Mexico from the Caribbean: c. 70,000 sq mi (181,299 sq km)

   also
2. state of Mexico, on this peninsula: 15,189 sq mi (39,339 sq km); pop. 1,363,000; cap. Mérida