| secret agent(noun, expression, idiom, plant, agent) |
| agent(noun, plant, operative, informer) |
| double agent(noun, expression, plant, agent) |
| emissary(noun, plant, watch, agent) |
| undercover agent(noun, expression, idiom, plant, watch) |
| infiltrator(noun, plant, detective, intruder) |
| informer(noun, plant, agent, operative) |
| lookout(noun, plant, watch, agent, warning) |
| spook(noun, plant, agent, operative) |
| detective(noun, plant, watch, agent) |
| espionage agent(noun, expression, plant, agent) |
| finger(noun, point, head, sneak) |
| inside agent(noun, expression, plant, agent) |
| operative(noun, plant, agent, detective) |
| patrol(noun, plant, watch, agent, warning) |
| picket(noun, plant, watch, agent, warning) |
| plant(noun, agent, operative, sneak) |
| scout(noun, plant, watch, agent, warning) |
| sleuth(noun, plant, watch, agent) |
| snoop(noun, plant, agent, operative) |