UNDEFENDED Synonyms: 49 Similar and Opposite Words

undefended

adjective

ˌən-di-ˈfen-dəd

Definition of undefended

as in vulnerable

lacking protection from danger or resistance against attack the cowardly soldiers fled, leaving the palace undefended

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Antonyms & Near Antonyms

Example Sentences

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.

Recent Examples of undefended The lack of range of Coastal Command aircraft left an undefended area known as the Mid-Atlantic Gap, rendering merchant shipping and their escorts without air cover and vulnerable to attack. — Mark Wood, TheWeek, 7 Jan. 2026 Trouba opened the scoring in the first period with an undefended slap shot after an egregious Blackhawks turnover. — CBS News, 7 Dec. 2025 Mark Collins, who was born and raised in Newfoundland, Canada, said Canadians have long treasured their friendship with the United States and the fact that the US-Canada border is the longest undefended border on the planet. — Matt Egan, CNN Money, 13 Oct. 2025 Like the global undersea cable network, the United States’ deep-water drilling infrastructure is rapidly expanding while remaining almost entirely undefended. — Robert Martinage, Foreign Affairs, 1 Jan. 2015 See All Example Sentences for undefended

Recent Examples of Synonyms for undefended

Adjective

The fact is, the bill helps to preserve Medicaid for those who need it most, including low-income families, persons with disabilities, and other vulnerable populations.

— Arkansas Online, Arkansas Online, 27 Oct. 2026
But that leaves the intricate energy system vulnerable to shocks.

— Matt Egan, CNN Money, 26 Oct. 2026

Definition of vulnerable

Adjective

That’s not because Crystal soft-pedals the emotional horror of returning to your home to find charred remains after watching, helpless, as flames took the locus of all your best memories.

— Chris Jones, Chicago Tribune, 22 Oct. 2026
That’s not because Crystal soft-pedals the emotional horror of returning to the charred remains of your home after watching, helpless, as flames took the locus of all your best memories.

— Chris Jones, New York Daily News, 21 Oct. 2026

Definition of helpless

Adjective

Kirshner says most units aren’t susceptible and that the issues appear quickly on units with the defect.

— Jay Peters, The Verge, 26 Oct. 2026
Microwave weapons can address groups of small aircraft, interceptors can physically destroy individual threats, electronic warfare can disrupt susceptible communications, and lasers can interfere with optical sensors.

— Kaif Shaikh, Interesting Engineering, 25 Oct. 2026

Definition of susceptible

Adjective

However, the fibers cannot simply be dropped into the ocean unprotected.

— Kaif Shaikh, Interesting Engineering, 13 Oct. 2026
However, during the same season, more than a third of the state’s children went unprotected, and many older Marylanders eligible for the RSV vaccine never received it.

— Adejare Atanda, Baltimore Sun, 13 Oct. 2026

Definition of unprotected

Browse Nearby Words

undefeated

undefended

undefiled

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“Undefended.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/undefended. Accessed 28 Oct. 2026.

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Synonyms of undefended

adjective

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