limitrophe
adjective
lim·i·trophe ˈli-mə-ˌtrōf 
-ˌtrȯf
: situated on a border or frontier : adjacent
the area limitrophe to the river
Word History
Etymology
French, from Late Latin limitrophus bordering upon, literally, providing subsistence for frontier troops, irregular from Latin limit-, limes boundary + Greek trophos feeder, from trephein to nourish
First Known Use
1763, in the meaning defined above