| spy(noun, person, plant, radical, goad) |
| intelligence agent(noun, radical, spy, operative, detective) |
| double agent(noun, expression, plant, agent, spy) |
| operative(noun, plant, agent, radical, spy) |
| informer(noun, plant, agent, spy, operative) |
| scout(noun, plant, agent, spy, operative) |
| mole(noun, plant, agent, spy, operative) |
| undercover agent(noun, expression, plant, agent, spy) |
| intelligence officer |
| agent(noun, plant, spy, operative, mole) |
| cross-questioner |
| detective(noun, plant, agent, spy, operative) |
| espionage agent(noun, expression, plant, agent, operative) |
| infiltrator(noun, plant, spy, mole, detective) |
| inside man(noun, spy) |
| plant(noun, agent, spy, operative, mole) |
| spook(noun, plant, agent, operative, mole) |
| spotter(noun, plant, agent, operative, mole) |
| squealer |
| undercover man(noun, spy) |