as in vulnerable
lacking protection from danger or resistance against attack
the cowardly soldiers fled, leaving the palace undefended
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Example Sentences
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Recent Examples of undefended
The buses usually took the Peace Bridge to cross the world’s longest undefended border, slowing to 30 mph over the Niagara River before pulling into the U.S. Customs and Border Protection processing center.
—
Tim Graham, New York Times, 9 July 2025
Yet after centuries of peace, with the two countries now sharing the longest undefended border in the world, the timing normally feels less like dueling celebrations than a week-long joint birthday party.
—Zack Beauchamp, Vox, 2 July 2025
Our two nations enjoy the world’s longest undefended border, largest trading partnership, and nearly a century of military cooperation, from the beaches of D-Day to the fight against al-Qaeda in Afghanistan.
—Ian Cooper, Sun Sentinel, 5 May 2025
Ukraine says that would amount to surrender and leave it undefended if Moscow attacks again.
—USA Today, 22 Apr. 2025
See All Example Sentences for undefended
Tim Graham, New York Times, 9 July 2025
Yet after centuries of peace, with the two countries now sharing the longest undefended border in the world, the timing normally feels less like dueling celebrations than a week-long joint birthday party.
—Zack Beauchamp, Vox, 2 July 2025
Our two nations enjoy the world’s longest undefended border, largest trading partnership, and nearly a century of military cooperation, from the beaches of D-Day to the fight against al-Qaeda in Afghanistan.
—Ian Cooper, Sun Sentinel, 5 May 2025
Ukraine says that would amount to surrender and leave it undefended if Moscow attacks again.
—USA Today, 22 Apr. 2025
See All Example Sentences for undefended
Recent Examples of Synonyms for undefended
Adjective
-
If an entrance hole is too large, smaller nesting birds will be vulnerable to predators and invasive species, including house sparrows, larger birds of prey, squirrels, snakes and even cats, which Hamlin says are birds’ top predators.—
Dallas Morning News,
Dallas Morning News,
6 Jan. 2026
-
People who have weakened immune systems or existing lung and heart disease are most vulnerable to cardiac complications from the flu.—
Helen Carefoot,
Flow Space,
6 Jan. 2026
Adjective
-
People eventually outgrow the helpless-baby stage.—
Anna Louie Sussman,
The Atlantic,
7 Nov. 2025
-
Without money and without a means to earn it, women are helpless to determine the course of their own lives.—
Literary Hub,
Literary Hub,
6 Nov. 2025
Adjective
-
The human brain is highly susceptible to often unproductive mind-wandering, and modern technology has only made the problem worse.—
Harvard Business Review,
Harvard Business Review,
7 Jan. 2026
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Common Pests and Diseases Like all plants, hoyas can be susceptible to pests and diseases.—
SJ McShane,
Martha Stewart,
7 Jan. 2026
Adjective
-
Although Hall won his third Vezina Trophy — at the time awarded to the goalies on the team that allowed the fewest goals — in 1966-67, the Hawks left him unprotected in the NHL expansion draft, and the Blues pounced.—
Chris Kuc,
Chicago Tribune,
8 Jan. 2026
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That selection is lottery protected in 2027 or otherwise unprotected in 2028.—
Ira Winderman,
Sun Sentinel,
7 Jan. 2026
Cite this Entry
“Undefended.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/undefended. Accessed 11 Jan. 2026.
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