frontier

American  

[fruhn-teer, fron-, fruhn-teer] / frʌnˈtɪər, frɒn-, ˈfrʌn tɪər /

noun

• frontiers
  plural

1. the part of a country that borders another country; boundary; border.

2. the land or territory that forms the furthest extent of a country's settled or inhabited regions.

3. Often frontiers.

   1. the limit of knowledge or the most advanced achievement in a particular field.

      the frontiers of physics.

   2. an outer limit in a field of endeavor, especially one in which the opportunities for research and development have not been exploited.

      the frontiers of space exploration.

4. Mathematics. boundary.

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adjective

1. of, relating to, or located on the frontier.

   a frontier town.

frontier British  

/ frʌnˈtɪə, ˈfrʌntɪə /

noun

1. 1. the region of a country bordering on another or a line, barrier, etc, marking such a boundary

   2. ( as modifier )

      a frontier post

2. 1. the edge of the settled area of a country

   2. ( as modifier )

      the frontier spirit

3. (often plural) the limit of knowledge in a particular field

   the frontiers of physics have been pushed back

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Synonym Usage

See boundary.

Other Word Forms

Derived Forms

• semifrontier
  noun
• frontierless
  adjective
• frontierlike
  adjective
• transfrontier
  adjective

Inflected Forms

Nouns

• frontiers
  plural

Etymology

Origin of frontier

1350–1400; Middle English frounter < Old French frontier, equivalent to front (in the sense of opposite side; see front) + -ier -ier ²

Explanation

A frontier represents uncharted territory. It could be a remote piece of land or a new field of study, but if someone calls it "the frontier," you are challenged to explore it. The noun frontier has several meanings. It can refer to the wilderness at the edge of a settled area (picture covered wagons pushing westward) or it can mean a field of study that has not yet been explored (picture genetically engineering pet dinosaurs). Deriving from "the front line of an army," a frontier can be thought of as an offensive line in a battle — always pushing forward, trying to conquer new territory.

Example Sentences

See Examples For:

frontier frontiers

The Rhine—which, as Mr. Winder writes, served “both as a frontier and a highway,” simultaneously connecting and separating Germany, France and Italy—was the most unquiet of the three.

From The Wall Street Journal ● Aug. 21, 2026

The next frontier is not merely knowing what we have wanted before.

From Salon ● Aug. 20, 2026

A steady buzz is growing around China as advanced robotics emerges as the next frontier of the global AI boom, encompassing both investor enthusiasm and alarm from rivals such as the United States.

From Barron's ● Aug. 19, 2026

"The capabilities of frontier models are rapidly accelerating," the company said.

From BBC ● Aug. 19, 2026

Dressed in rugged deerskin hunting shirts, the Virginians met up with some locals from nearby Marblehead, Massachusetts, who made fun of the Virginians and their frontier outfits.

From "In the Shadow of Liberty" by Kenneth C. Davis

Terry says Qantas is conquering "one of the last frontiers in commercial aviation".

From BBC ● Jun. 26, 2026

US astronaut Christina Koch, the first woman to take part in a lunar mission, was on Wednesday named the winner of a top Spanish prize for having "helped extend the frontiers of humanity".

From Barron's ● Jun. 17, 2026

After IBM’s Deep Blue supercomputer scored a landmark victory over chess champion Garry Kasparov in 1997, researchers sought new simulations to push the frontiers of machine intelligence.

From MarketWatch ● May 23, 2026

"This study opens up new frontiers in research on human evolution," adds Professor Eleanor Scerri of the Max Planck Institute of Geoanthropology, also senior author of the study.

From Science Daily ● May 3, 2026

“We were expanding beyond ourselves, beyond our own planet, pushing back frontiers, bettering ourselves.”

From "A Deadly Wandering: A Mystery, a Landmark Investigation, and the Astonishing Science of Attention in the Digital Age" by Matt Richtel