sleeper cell

Noun

 * 1) A group of people (sleepers) who inconspicuously remain dormant in a community until activated, by a prearranged signal, in order to perform acts of espionage, sabotage, or terrorism.

Translations

 * Chinese:
 * Mandarin:
 * Finnish: nukkuva solu
 * French:
 * German: Schläferzelle
 * Portuguese: célula adormecida, célula dormente
 * Russian: спя́щая яче́йка