: any one of five levels of U.S. military defense readiness that are ranked from 5 to 1 according to the perceived threat to national security, with 1 indicating the highest level of perceived threat
It was determined that the secretary of Defense had the authority to declare DEFCON 3 on his authority.—
Stephen A. Cambone
—sometimes used figurativelyStephen A. CamboneDon't even mention the privatization of Social Security that will take Congress to DEFCON 1.—Sam Allis
Sam AllisExamples of DEFCON in a Sentence
Recent Examples on the Web
Anthropic, OpenAI, and DeepMind have all outlined escalating levels of safety precautions—akin to the military’s DEFCON system—corresponding to more powerful AI models.
—Matteo Wong, The Atlantic, 21 Aug. 2025
Months before the event, my mother went to DEFCON 1.
—Lian Dolan, People.com, 20 May 2025
Then came four points in 26 minutes in a Game 4 buzzer-beating win, as interim head coach David Adelman went full DEFCON 5 and played Nikola Jokic the whole second half.
—Luca Evans, Denver Post, 29 Apr. 2025
As a result, in all collective bargaining negotiations since 1998, MLB players theoretically had the option of decertifying the union and pursuing an antitrust class action lawsuit.
DEFCON What?
—Chris Deubert, Forbes, 7 Mar. 2025
With accolades including a DEFCON Black Badge—one of the most prestigious awards in the cybersecurity community—Alethe has firsthand knowledge of how people, policies and technologies interplay in protecting companies.
—Lauren Carpenter, USA TODAY, 30 Jan. 2025
Only twice has the US reached DEFCON 2, meaning full alert/war imminent.
—Matthew Wills, JSTOR Daily, 3 Jan. 2025
All those weird sensors in your brain that cry out for deliciousness are at DEFCON 1 all day.
—Claire Bugos, Verywell Health, 30 July 2024
Things nearly got even worse: after the Israelis recovered from their initial shock and began reversing Egyptian gains, Moscow threatened unilateral military measures, prompting the United States to go to DEFCON 3 and put its nuclear forces on worldwide alert.
—Gabriel Scheinmann, Foreign Affairs, 17 May 2015
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Matteo Wong, The Atlantic, 21 Aug. 2025
Months before the event, my mother went to DEFCON 1.
—Lian Dolan, People.com, 20 May 2025
Then came four points in 26 minutes in a Game 4 buzzer-beating win, as interim head coach David Adelman went full DEFCON 5 and played Nikola Jokic the whole second half.
—Luca Evans, Denver Post, 29 Apr. 2025
As a result, in all collective bargaining negotiations since 1998, MLB players theoretically had the option of decertifying the union and pursuing an antitrust class action lawsuit.
DEFCON What?
—Chris Deubert, Forbes, 7 Mar. 2025
With accolades including a DEFCON Black Badge—one of the most prestigious awards in the cybersecurity community—Alethe has firsthand knowledge of how people, policies and technologies interplay in protecting companies.
—Lauren Carpenter, USA TODAY, 30 Jan. 2025
Only twice has the US reached DEFCON 2, meaning full alert/war imminent.
—Matthew Wills, JSTOR Daily, 3 Jan. 2025
All those weird sensors in your brain that cry out for deliciousness are at DEFCON 1 all day.
—Claire Bugos, Verywell Health, 30 July 2024
Things nearly got even worse: after the Israelis recovered from their initial shock and began reversing Egyptian gains, Moscow threatened unilateral military measures, prompting the United States to go to DEFCON 3 and put its nuclear forces on worldwide alert.
—Gabriel Scheinmann, Foreign Affairs, 17 May 2015
Cite this Entry
“DEFCON.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/DEFCON. Accessed 4 Nov. 2025.
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