Frontier

Origin

From Old French fronter (whence Modern French frontière), from front.

Noun

1. That part of a country which fronts or faces another country or an unsettled region; the marches; the border, confine, or extreme part of a country, bordering on another country; the border of the settled and cultivated part of a country; as, the frontier of civilization.
• 1979, Richard Elphic and Hermann Guilomee (editors), The shaping of South African Society, 1652 - 1820, page 297:Unlike a boundary, which evokes the image of a line on a map and demarcates spheres of political control, the frontier is an area where colonisation is taking place....no authority is recognised as legitimate by all parties or is able to excersise undisputed control over the area.
2. (obsolete) An outwork of a fortification.
• ShakespearePalisadoes, frontiers, parapets.

Adjective

1. Lying on the exterior part; bordering; conterminous.a frontier town