Some airports of big cities are, in fact, technically speaking in a "very near municipality" which is not the main city itself.
For example the airport BCN serving "Barcelona" is, in fact, placed in the city "El Prat del Llobregat" which is 15 Km south from Barcelona.
Or for example the airport CDG serving "Paris" is, in fact, at the town "Roissy" 25 Km northeast from Paris.
I "think" (but can't confirm) I have heard the term "Service City" to refer to the "main city" the airport is conceptually associated to. For example to say "CDG's service city is Paris".
I'm trying to confirm this terminology with no luck.
Can anyone confirm, if this term is correct and provide any public source defining the term? If the term is not correct, what would be the correct one?