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"México" is a proper noun which is often translated as "Mexico", and "DF" is an abbreviation which is often translated as "Mexico City". Learn more about the difference between "México" and "DF" below.
DF(
deh
-
ehfeh
)An abbreviation is the shortened form of a word or group of words (e.g., "UFO" = "unidentified flying object"; "p." = "page").
a. Mexico City
La única parte de México que conozco es el DF.The only part of Mexico I ever visited is Mexico City.