Mexico UK /ˈmɛk.sɪ.kəʊ/US /ˈmɛk.sɪ.koʊ/ noun3 •A country in North America, located south of the United States, and northwest of Guatemala and Belize from Central America. Official name: United Mexican States. •(rare) Ellipsis of Mexico City: the capital city of Mexico. •Ellipsis of the State of Mexico: a state of Mexico. Capital: Toluca.