Frontier /(?)/

Fron·tier

Frontier

n.
  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.
  2. An outwork. (Fort.) [Obs.]
    Palisadoes, frontiers, parapets.

Frontier

a.
  1. Lying on the exterior part; bordering; conterminous; as, a frontier town.
  2. Of or relating to a frontier.

Frontier

v. i.
  1. To constitute or form a frontier; to have a frontier; -- with on. [Obs.]