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

As AI labs pushed the envelope with ever more powerful frontier models, Microsoft was developing a parallel concept of the “frontier company,” built on principles that reflected AI.

From The Wall Street Journal ● Sep. 17, 2026

China, long seen as trailing the United States on frontier AI, has been closing that gap fast.

From Barron's ● Sep. 17, 2026

The sky was a frontier, and a macho one.

From Los Angeles Times ● Sep. 16, 2026

Alphabet is instead choosing to funnel resources to its Google Cloud business, which Nathanson believes is a more profitable strategy than “chasing frontier leadership at any cost.”

From MarketWatch ● Sep. 16, 2026

Most of them wore cheap felt three-cornered hats and frontier shirts that tied at the collar.

From I Survived the American Revolution, 1776 by Lauren Tarshis

Among its next frontiers is wealth management, with advisers at big banks among those already using its platform.

From The Wall Street Journal ● Sep. 10, 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

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

He could not control the news, and the front page was a source of continuous aggravation to a man who wanted life to be cut into symmetrical quadrants and accessible frontiers.

From "The Great Santini" by Pat Conroy