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.

---

adjective

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

   a frontier town.

frontier British  

/ ˈfrʌntɪə, frʌnˈtɪə /

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

---

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

For now, hyperscalers are shouldering the cost of financing frontier AI labs that, as Storm put it, “do not have a credible path to profitability.”

From Los Angeles Times ● Oct. 25, 2026

Five years ago, the engineers on the frontier of artificial intelligence trained a model to solve thousands of basic math problems.

From The Wall Street Journal ● Oct. 24, 2026

Meanwhile, investors are still waiting for the initial public offerings of frontier model makers Anthropic and OpenAI.

From MarketWatch ● Oct. 20, 2026

The South later resumed border loudspeaker broadcasts for the first time in six years, including K-pop and international news, while the North began transmitting strange, eerie sounds across the frontier, unsettling South Korean residents.

From Barron's ● Oct. 20, 2026

Gist had explored the frontier wilderness along the Ohio River as far as where Cincinnati is today.

From "George Washington, Spymaster" by Thomas B. Allen

“There’s a whole bunch of frontiers, actually,” Almeida said.

From The Wall Street Journal ● Oct. 2, 2026

Although the research focused on two regions of the Amazon, the scientists say its conclusions may also apply to tropical deforestation frontiers elsewhere in the world.

From Science Daily ● Sep. 21, 2026

Actually, I take that back – consulting her most devoted fans will open new frontiers for you.

From Salon ● Aug. 29, 2026

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

From BBC ● Jun. 26, 2026

The frontiers between the three superstates are in some places arbitrary, and in others they fluctuate according to the fortunes of war, but in general they follow geographical lines.

From "1984" by George Orwell

Random Word

Spin the wheel and learn a new word!

---