the isthmian tract between the southern Rocky Mountains and the northern tip of the Andes (or, generally, from the southern border of the United States to the northern border of Colombia), marking the territory transitional from North America to South America. The difference between this designation and Central America is that Middle America includes Mexico and the Caribbean islands.
MIDDLE AMERICA
Meaning of MIDDLE AMERICA in English
Britannica English vocabulary. Английский словарь Британика. 2012