Princeton's WordNet

1. United States Secret Service, US Secret Service, USSS, Secret Service, SS(noun)

   the United States intelligence agency that protects current and former presidents and vice presidents and their immediate families and protects distinguished foreign visitors; detects and apprehends counterfeiters; suppresses forgery of government securities and documents

2. Schutzstaffel, SS(noun)

   special police force in Nazi Germany founded as a personal bodyguard for Adolf Hitler in 1925; the SS administered the concentration camps