Definition of DEFCON
: 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 figuratively <Don't even mention the privatization of Social Security that will take Congress to DEFCON 1. — Sam Allis>
Origin and Etymology of defcon
First Known Use: 1962
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