• (GA) IPA: /fɹʌnˈtɪɹ/
• (RP) IPA: /fɹʌnˈtɪə/

frontier (plural frontiers)

1. The part of a country which borders or faces another country or unsettled region
2. The most advanced or recent version of something; leading edge.

   the frontier of civilization

3. (obsolete) An outwork of a fortification.
   • c. 1597, William Shakespeare, “The First Part of Henry the Fourth, […]”, in Mr. William Shakespeares Comedies, Histories, & Tragedies: Published According to the True Originall Copies (First Folio), London: Printed by Isaac Iaggard, and Ed[ward] Blount, published 1623, OCLC 606515358 ↗, [Act II, scene iii]:

     thou hast talk'd. Of sallies and retires, of trenches, tents,
     Of palisadoes, frontiers, parapets

• (part of country bordering another) marches; the border

• French: frontière
• German: Grenze, Landesgrenze, Staatsgrenze
• Italian: confine, frontiera
• Portuguese: fronteira
• Russian: грани́ца
• Spanish: frontera

1. Lying on the exterior part; bordering; coterminous.

   a frontier town

• Russian: приграни́чный

frontier (frontiers, present participle frontiering; past and past participle frontiered)

1. (intransitive) To live as pioneers on frontier territory.
2. (transitive, obsolete) To place on the frontier.

1. An unincorporated community in Koochiching, Minnesota.
2. A city in North Dakota.
3. An unincorporated community in Lincoln County, Wyoming.
4. A village in Saskatchewan.