Noun | 1. | Ballistic Missile Defense Organization - an agency in the Department of Defense that is responsible for making ballistic missile defense a reality Defense Department, Department of Defense, DoD, United States Department of Defense, Defense - the federal department responsible for safeguarding national security of the United States; created in 1947 bureau, federal agency, government agency, agency, office, authority - an administrative unit of government; "the Central Intelligence Agency"; "the Census Bureau"; "Office of Management and Budget"; "Tennessee Valley Authority" |