limitrophe
Border, frontier; being or existing along a border or frontier.
As was stipulated in the Firman of 1249, Servia shall be bound to send back home all emigrants from the limitrophe provinces, and, with the exception of the fortresses which exist in Servia ab antiquo, all fortifications subsequently erected […]
Where it comes from
From French limitrophe, from Latin limitrophus.
Adapted from the Wiktionary entry limitrophe (CC BY-SA 4.0).