fail-deadly /ˌfeɪlˈdɛdli/ adjective1 •Of a nuclear weapons strategy: encouraging deterrence by guaranteeing an automatic, immediate, and overwhelming response to an attack, even if the command-and-control infrastructure has been damaged by the enemy's first strike.If one were to assume a more traditional Realist image of human fallibility, then one's confidence in the safety of the elaborate nuclear "fail deadly" deterrence order might not be so sanguine. — 1993