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
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
Robert Klitzman
frontier
adjective
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
Procurement, Deregulation, And Political Pushback The plan calls for updates to federal procurement rules to ensure that frontier models used by the government are free from top-down ideological bias and aligned with principles of free expression.
—Paulo Carvão, Forbes.com, 23 July 2025
Learn About Historic Fort King This U.S. Army frontier fort played an important role in the Second Seminole War when the Seminole fought to protect their native land against American settlers.
—Tara Massouleh McCay, Southern Living, 22 July 2025
Meanwhile, leaders will need to develop policies to share sensitive, proprietary information on developments in frontier AI with partners and allies.
—Matan Chorev, Foreign Affairs, 22 July 2025
William Campbell | Getty Images Part of the Cowboy State's allure is its frontier character.
—Scott Cohn, CNBC, 18 July 2025
See All Example Sentences for frontier
Examples are automatically compiled from online sources to
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Paulo Carvão, Forbes.com, 23 July 2025
Learn About Historic Fort King This U.S. Army frontier fort played an important role in the Second Seminole War when the Seminole fought to protect their native land against American settlers.
—Tara Massouleh McCay, Southern Living, 22 July 2025
Meanwhile, leaders will need to develop policies to share sensitive, proprietary information on developments in frontier AI with partners and allies.
—Matan Chorev, Foreign Affairs, 22 July 2025
William Campbell | Getty Images Part of the Cowboy State's allure is its frontier character.
—Scott Cohn, CNBC, 18 July 2025
See All Example Sentences for frontier
Cite this Entry
“Frontier.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/frontier. Accessed 29 Jul. 2025.
Copy CitationKids Definition
frontier
noun
fron·tier
ˌfrən-ˈti(ə)r
frän-
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
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