frontier

noun

fron·​tier ˌfrən-ˈtir 

ˈfrən-ˌtir,

frän-ˈtir,

ˈfrän-ˌtir 

1

a

: a border between two countries

the frontier between Canada and the U.S.

b

obsolete : a stronghold on a frontier

2

a

: a region that forms the margin of settled or developed territory

were sent on an expedition to explore the western frontier

b

: the farthermost limits of knowledge or achievement in a particular subject

frontiers in immunology

c

: a line of division between different or opposed things

the frontiers separating science and the humanities

—R. W. Clark

d

: a new field for exploitative or developmental activity

… the brain lies before us as one of the last scientific frontiers here on earth.

—Robert Klitzman

frontier adjective

Synonyms

• border
• borderland
• march

Examples of frontier in a Sentence

the frontier between Canada and the U.S.

They were sent on an expedition to explore the western frontier.

Recent Examples on the Web

An anonymous fertility startup founder IVF and egg-freezing now appear to be the newest frontier for the problem. —Alexandra S. Levine, Forbes, 14 Oct. 2024

In the early 1800s, Arkansas was the western frontier. —Curtis Varnell The Timepiece, arkansasonline.com, 13 Oct. 2024

Its vast frontier, on land and at sea, remained largely peaceful as China’s economy grew to become the world’s second-largest. —New York Times, 11 Oct. 2024

Kena Betancur/Getty Images Contrasting approaches to AI models One of the biggest differences between Zoom’s approach to AI and that of Microsoft and Google is access to the most sophisticated frontier models. —Bysharon Goldman, Fortune, 9 Oct. 2024

Word History

Etymology

Middle English fronter, from Anglo-French frountere, fronter, from front

First Known Use

15th century, in the meaning defined at sense 1a

Kids Definition

frontier

noun

fron·​tier ˌfrən-ˈti(ə)r  frän- 

1

: a border between two countries

2

a

: a region that forms the edge of the settled part of a country

b

: the outer limits of knowledge or achievement

the frontiers of science

frontier adjective