frontier

Plural: frontiers

Noun

• A border separating two countries, or the edge of settled territory.
• a wilderness at the edge of a settled area of a country
  • "the individualism of the frontier in Andrew Jackson's day"
• an international boundary or the area (often fortified) immediately inside the boundary
• an undeveloped field of study; a topic inviting research and development
  • "he worked at the frontier of brain science"
• The part of a country which borders or faces another country or unsettled region.
• The most advanced or recent version of something; the leading edge.
• An outwork of a fortification.

Verb

• To live as pioneers on frontier territory.
• To place on the frontier.

Examples

• He pushed the frontier of his vocabulary, daring to play an unknown word.
• the frontier of civilization
• the frontier of solid state electronics

Synonyms

border#Noun, borderland, march#Noun_2, marches#Noun, marchland