Webster’s Revised Unabridged Dictionary · 1913
Frontier
Fron′tier (frŏn′tēr; 277), 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. Shak.
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.