armed forces, armed services, military, military machine, war machine - the military forces of a nation; "their military is the largest in the region"; "the military machine is the same one we faced in 1991 but now it is weaker"

counterspy, mole - a spy who works against enemy espionage

double agent - a spy who works for two mutually antagonistic countries

espionage agent - someone employed to spy on another country or business competitor

foreign agent - a spy for a foreign country

infiltrator - someone who takes up a position surreptitiously for the purpose of espionage

intelligence agent, intelligence officer, operative, secret agent - a person secretly employed in espionage for a government

sleeper - 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

Margarete Gertrud Zelle, Mata Hari - Dutch dancer who was executed by the French as a German spy in World War I (1876-1917)

snoop, snooper - a spy who makes uninvited inquiries into the private affairs of others

looker, spectator, viewer, watcher, witness - a close observer; someone who looks at something (such as an exhibition of some kind); "the spectators applauded the performance"; "television viewers"; "sky watchers discovered a new star"

shadower, tail, shadow - a spy employed to follow someone and report their movements

sight - catch sight of; to perceive with the eyes; "he caught sight of the king's men coming over the ridge"

monitor, ride herd on, supervise - keep tabs on; keep an eye on; keep under surveillance

enquire, investigate, inquire - conduct an inquiry or investigation of; "The district attorney's office investigated reports of possible irregularities"; "inquire into the disappearance of the rich old lady"