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
China’s open-source DeepSeek model replicated frontier American models’ capabilities cheaper while using older chips.
—MSNBC Newsweek, 8 Oct. 2025
New Shepard has carried some famous people to and from the final frontier over the past few years.
—Mike Wall, Space.com, 8 Oct. 2025
From watching millennials normalize egg freezing to period tracking and fertility care, for many, menopause feels like the next frontier in reproductive autonomy—and patches symbolize both relief and rebellion.
—Lauryn Higgins, Flow Space, 8 Oct. 2025
Here’s how that research, pioneered more than 40 years ago, has led to new frontiers in modern physics, as well as 2025’s Nobel Prize in physics.
—Ethan Siegel, Big Think, 8 Oct. 2025
See All Example Sentences for frontier
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MSNBC Newsweek, 8 Oct. 2025
New Shepard has carried some famous people to and from the final frontier over the past few years.
—Mike Wall, Space.com, 8 Oct. 2025
From watching millennials normalize egg freezing to period tracking and fertility care, for many, menopause feels like the next frontier in reproductive autonomy—and patches symbolize both relief and rebellion.
—Lauryn Higgins, Flow Space, 8 Oct. 2025
Here’s how that research, pioneered more than 40 years ago, has led to new frontiers in modern physics, as well as 2025’s Nobel Prize in physics.
—Ethan Siegel, Big Think, 8 Oct. 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 10 Oct. 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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