The term 'Neighbor of Croatia' can be answered with two crossword solutions: Serbia (6 letters) and Bosnia (6 letters). Serbia is a country located in the Balkan Peninsula in southeastern Europe, bordered by Hungary to the north, Romania to the northeast, Bulgaria to the southeast, North Macedonia to the south, Croatia and Bosnia and Herzegovina to the west, and Montenegro to the southwest. Bosnia and Herzegovina is a country located in the western Balkans, bordering Croatia to the north, west, and south, Serbia to the east, and Montenegro to the southeast. Both countries are neighbors of Croatia.