Definition of "frontier" in English

noun

1. The part of a country which borders or faces another country or unsettled region.

   • the frontier of civilization

2. The most advanced or recent version of something; the leading edge.

   • Near-synonyms: vanguard, state of the art
   • the frontier of solid state electronics

3. (obsolete) An outwork of a fortification.

verb

1. (intransitive) To live as pioneers on frontier territory.

2. (transitive, obsolete) To place on the frontier.