| Noun | 1. | Transportation Security Administration - an agency established in 2001 to safeguard United States transportation systems and insure safe air travel Department of Transportation, DoT, Transportation - the United States federal department that institutes and coordinates national transportation programs; created in 1966 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" |