Fron"tier (?), n. [F. frontière, LL. frontaria. See Front.] 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. (Fort.) An outwork. [Obs.]

Palisadoes, frontiers, parapets.

Fron"tier, a. 1. Lying on the exterior part; bordering; conterminous; as, a frontier town.

2. Of or relating to a frontier. "Frontier experience." W. Irving.

Fron"tier, v. i. To constitute or form a frontier; to have a frontier; -- with on. [Obs.] Sir W. Temple.

• 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.
  
• An outwork.
  
• To constitute or form a frontier; to have a frontier; -- with on.
  
• Lying on the exterior part; bordering; conterminous; as, a frontier town.
  
• Of or relating to a frontier.