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

The good thing about these use cases is the compute and infrastructure intensity isn’t the same as the frontier models and race for AGI. —Daniel Newman, Forbes, 30 Dec. 2024

The frontier regiment was known for its infamous defeat at the Battle of Little Bighorn under George Custer 14 years prior. —Eli Wizevich, Smithsonian Magazine, 29 Dec. 2024

Software — the next AI frontier Investors also view software as an area that’s rife with opportunity in 2025 as the AI buildout reaches the use case stage. —Samantha Subin, CNBC, 27 Dec. 2024

Moscow would then establish interlocking air defense systems along the NATO frontier, from the Black Sea to the Arctic. —Elaine McCusker, Foreign Affairs, 13 Dec. 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