Researcher

diligent and systematic inquiry or investigation into a subject in order to discover or revise facts, theories, applications, etc.

recent research in medicine.

a particular instance or piece of research.

to make researches; investigate carefully.

to make an extensive investigation into

to research a matter thoroughly.

noun

analyst , analyzer , clinician , experimenter , investigator , scientist , tester , inquisitor , prober , querier , quester , questioner