sleeper nest

English Thesaurus

1. a nest of sleepers awaiting a prearranged signal (noun.group)

hypernym	:	nest,
definition	:	a gang of people (criminals or spies or terrorists) assembled in one locality (noun.group)

member holonym	:	sleeper,
definition	:	a spy or saboteur or terrorist planted in an enemy country who lives there as a law-abiding citizen until activated by a prearranged signal (noun.person)