WordNet (r) 3.0 (2006):

INS
    n 1: an agency in the Department of Justice that enforces laws
         and regulations for the admission of foreign-born persons
         to the United States [syn: Immigration and Naturalization
         Service, INS]

Moby Thesaurus II by Grady Ward, 1.0:

33 Moby Thesaurus words for "ins":
   bureaucracy, directorate, hierarchy, higher echelons, higher-ups,
   holdover, incumbent, jack-in-office, lame duck, management,
   ministry, new broom, office-bearer, officeholder, officialdom,
   prelacy, president-elect, public official, public servant,
   ruling class, ruling classes, the Establishment,
   the administration, the authorities, the ingroup, the interests,
   the people upstairs, the power elite, the power structure, the top,
   them, they, top brass