| experimenter(noun, scientist) |
| scientist(noun, person, search, expert, first) |
| tester(noun, person, agent, hound, monitor) |
| checker |
| discoverer(noun, person, search, first) |
| examinant(noun, person, search, first) |
| operative(noun, plant, agent, mole, gumshoe) |
| pathfinder(noun, person, search, first) |
| prober(noun, person, investigate, ask, agent) |
| quester(noun, person, investigate, ask, agent) |
| watcher(noun, person, plant, search, agent) |
| agent(noun, person, plant, shadow, operative) |
| analyzer(noun, scientist) |
| assayer |
| auditor(noun, person) |
| evaluator(noun, examiner, questioner) |
| interrogator(noun, tester, examiner, regulator, questioner) |
| observer(noun, plant, agent, operative, informer) |
| pioneer(noun, person, search, first) |
| plainclothesman(noun, gumshoe, detective, sleuth) |