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.
Palisadoes, frontiers, parapets. Shak.