WordNet (r) 3.0 (2006):

USSS
    n 1: 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 [syn:
         United States Secret Service, US Secret Service,
         USSS, Secret Service, SS]